The cast of Night at the Museum, including Australian Rebel Wilson, spoke of the saga on the red carpet overnight. Source: AP

Actor Owen Wilson was visibly shocked when he heard about the commonly used jihadist flag being flown in Sydney while Sir Ben Kingsley expressed his distress over the hostage taking.

Ben Stiller was also shocked as was Australian actress Rebel Wilson after she received a telephone call from her family to allay any possible fears as both her sisters work in the Martin Place area.

Close to home ... Australian actress Rebel Wilson has two sisters who work around Martin Place in Sydney. Source: AFP

The actors were in London for a gala red carpet launch of their comedy Night at the Museum: Secret of the Tomb but as events unfolded in Sydney, they expressed their horror to News Corp Australia.

“God that’s shocking, how distressing over in Sydney,” Sir Ben said. Owen Wilson knew there was a hostage and siege situation but was shocked to hear reports of a jihadist flag popularly used by groups like Isis being displayed.

“I saw there was a hostage scene, ISIS is in Sydney? How many hostages, where in Sydney?” he asked before mouthing a swear word and as minders moved to answer his questions.

SIEGE OVER: POLICE STORM CAFE AND KILL GUNMAN

THE GUNMAN: WHO IS SHEIK MAN HARON MONIS?

RESCUED: WEEPING HOSTAGES FREED IN RAID

GLOBAL HORROR: WORLD WATCHES END OF SIEGE

Sombre proceedings ... Sir Ben Kingsley was shocked by the news. Source: AP

Rebel Wilson, who lives in Los Angeles but is due to fly home to Australia tomorrow, said she did not expect such horrible events in her home city of Sydney.

“I just turned the television on for 10 minutes this morning after I got a call from my family because both my sisters work there across the Martin Place area,” she said.

“They just said ‘have you heard’ and I said ‘no’ then turned the TV on for 10 minutes to see what was happening, geez it was terrible.”

Stiller said he couldn’t believe it was still going on after, at that point, more than 12 hours.

“It’s scary, really scary,” he said.

Australian celebrities shared their thoughts and condolences on social media too:

CelebCon: Prayers for Sydney

Meanwhile, British Prime Minister David Cameron, who had already offered his support to counterpart Tony Abbott, was tracking events during the day.

“It is obviously very concerning, what has taken place, albeit on the other side of the world but in a country very close to our hearts, and it is a reminder of the threat we face from Islamic extremist terror,” he said ahead of delivering a major speech on the British economy.

“Obviously we will always look at these cases to see if there’s things that we can learn, but our thoughts right now are with the hostages and hope it can be resolved.”

‘Our thoughts are with the hostages’ ... British Prime Minister David Cameron offered his support to Tony Abbott. Source: AFP