• 8.00pm: Police arrest two males and pin another down on Swanston St
• 8.30pm: Police are seen conducting frequent weapons searches on youths outside St Paul’s Cathedral
• 8.50pm: Police handcuff another male on the Federation Square steps and hold him for 15 minutes
• 9.15pm: About 20 incident response officers flood Fed Square forming a barrier
• 9.35pm: Twelve plain-clothes detectives in police vests stake out Federation Square
• 9.40pm: Another male, who appears to be under the influence of alcohol or drugs, is handcuffed by police
• 10.30pm: Following a random search a male was caught by police carrying a screwdriver which was taken off him
• 10.55pm: A group of youths suddenly swarm on Federation Square. Police use pepper spray and draw batons
• 11.10pm: The central section of Federation Square is blocked off by mounted police. Three people are affected by pepper spray
• 11.11pm: A man is arrested on the Princes Bridge after about 15 officers surround him. Mounted police start moving towards Flinders St
• 11.20pm: Another two people arrested on the bridge. A man allegedly tries to smash a camera belonging to a Sunday Herald Sun photographer. Mounted police again move in as groups of men and police spill out along the bridge towards Southbank
• 11.27pm: Police start descending on the tram stop on Swanston St and close off Flinders St outside the station entrance
• 12.05am: Another fracas spills up Flinders Street to Russell St. The group chant “Westside motherf**kers.” Police charge at them and form a barrier pushing the crowd away from the city. Batons are drawn and the mounted police disperse the group
• 1:15am: — A large group of youths has congregated outside the Flinders Lane police station with Special Response Officers forming a barrier and preventing anyone from travelling between Flinders Lane and Flinders Street.

At about 1.15am, a group of youths congregated outside the Flinders Lane police station. Special Response Officers formed a barrier and prevented anyone from travelling between Flinders Lane and Flinders Street.

Police continued to try and disperse the large groups of youths still loitering in the area with frequent scuffles breaking out and pepper spray deployed.

The Sunday Herald Sun witnessed police arrest another male outside of Hungry Jacks shortly after 1am.

Police closed off Federation Square to the public and were attempting to move the youths to the train station and onto trains.

Authorities patrolled along the Yarra River, searching festival-goers and jumping on the first signs of trouble into the early hours of Sunday.

The most serious altercation occurred about 11pm last night at Federation Square when police deployed pepper spray and pulled out their batons after youths swarmed the area.

Two men were left wincing in pain, affected by the pepper spray.

The incident appeared to start with an argument between two groups of young men.

A second fracas occurred shortly after causing the mounted police to move in, with police trying to shift hundreds of people off the stairs at Federation Square.

Troublemakers were left in no doubt about who was in control after police were last year caught out when dozens of youths rioted.

Police officers were put on high alert after receiving intelligence that 80-100 troublemakers were heading into the city by train.

The large group was allegedly planning to carry out a number of crimes including mobile phone thefts, snatch and grab offences, car-jackings, and assaults on members of the public and police officers.

The intelligence suggested gang members were looking to “cause as much havoc as possible” in the city between 1am and 2am.

Police also received information that a brawl between two rival groups was scheduled for Federation Square at midnight.

Dozens of people were searched for weapons throughout the night as police used their stop and search powers.

The State Government had earlier designated the CBD and Moomba locations subject to these powers.

At least 12 people had been arrested, including one for carrying a weapon, four for behavioural issues and two for carrying alcohol.

Throughout the night, the Sunday Herald Sun saw dozens of people being searched by police, and one youth, who spat and swore at police, being arrested.

A balaclava was found in the bag of one youth in a group of young men who were searched after a tip-off from event security that the teenagers may have been selling counterfeit ride tickets.

When asked by the Sunday Herald Sun why he was carrying the mask, the young man said it was “to take photos in” and then post online.

Police told him to throw it away immediately.

More than 100 officers monitored the crowds on the banks of the Yarra River and throughout Alexandra Gardens during festival fireworks.

Another dozen officers were at the festival’s skate park, where teenagers were congregating.

Two males were arrested and third pinned down outside Hungry Jack’s on Swanston St.

The man, who was pinned down repeatedly, swore and yelled at police “f--- youse all”.

Robert, who works in the area, witnessed the incident unfold.

“The male queried the police and then he started to mouth off at the coppers and started swinging his arms at the police,” Robert said.

Another witness said the male was “out-of-order” because he “randomly started abusing police”. The man was released soon after.

Thousands of cheerful Melburnians had earlier flocked to the banks of the Yarra for the first day of the family festival.

Families said they were not hesitant to come back this year, despite last year’s violence.

“I’m glad there’s more police around. We weren’t hesitant, it makes us feel a bit more safe. There is a lot of police on the ground,” one man said.

EARLIER: POLICE were on high alert after posts on social media suggested up to 100 people were planning on heading to the city to disrupt Moomba.

It is understood officers were particularly concerned about ‘phone snatchers’ targeting people watching and filming the fireworks after a similar issue occurred at a family festival in Caroline Springs.

The Sunday Herald Sun witnessed police search a group a young men, some of African and Middle Eastern appearance, after being tipped-off by event security that the teenagers may have been selling counterfeit ride tickets.

The young men, understood to between 17 and 18 years old said it was their first time at the festival but they were not surprised they had been searched by police.

“I guess because of they way we look. They said they were searching for weapons and stuff but we’re just going about our business,” one teenager said.

Meanwhile thousands of Melburnians flocked to the city on Friday and Saturday.

Audiences were treated to the world’s best water-skiers and wakeboarders who performed awe-inspiring flips and tricks as they battled it out on the Yarra for the coveted Melbourne Masters title.

Scooters, skaters and BMX riders also flaunted their skills at the Riverslide Skate Park.

Police were overall happy with crowd behaviour despite five people being arrested on Friday night, one for possessing a weapon and four for behavioural issues.

Another eight were arrested for other reasons unrelated to Moomba festivities.

Roving performances, roaring rides, carnival-style games, food trucks and family-friendly fireworks will draw thousands again today.

The Birdman Rally will highlight festivities today from 11.30am while on Monday crowds will cheer on 2017’s Moomba monarchs chefs Guy Grossi and Karen Martini in the iconic parade.