A lone gunman fired shots from an assault rifle and set fire to gambling tables at Resort World Manila, resulting in the deaths of dozens of people. The attacker, whose motives are so far unclear, later killed himself, authorities said.

Attacks of this scale are rare in Manila, especially in upscale areas frequented by tourists, which typically have heavy security.

Philippine officials say they don't believe the assailant was motivated by terrorism. But the attack on a major hotel and casino complex near the capital's international airport could still hurt tourism, a key source of income for the developing country.

Nearly two-thirds of visitors to the Philippines in February flew into Manila, according to the country's Department of Tourism, making it the country's biggest arrival hub.

"People get good bang for their buck in the Philippines," said David Beirman, a senior lecturer specializing in tourism at the University of Technology Sydney. "But safety and security is now the number one factor in determining where tourists go. It used to be things like value for money, but that's changed. In the short term [the attack in Manila] is clearly going to have a negative impact on tourism."

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Shares in Travellers International Hotel Group, the company that runs the Manila resort, plunged almost 8% on Friday.

The attack's potential reverberations in the tourism industry could spoil a good run for the sector.

The Philippines has experienced a surge in visitors since 2010. Experts say that's thanks to the relatively stable political environment under former President Benigno Aquino III, as well as a marketing drive by the tourism board and the introduction of the country's first low-cost carrier, Cebu Pacific.

Just under 6 million visitors flocked to the Philippines last year, roughly triple the number that arrived in 2000.

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Travel accounted for about 8% of gross domestic product in 2016, according to the World Travel & Tourism Council. That's higher than the 3%-5% average of most countries, said Bob McKercher, a professor of tourism management at Hong Kong Polytechnic University.

Tourism numbers have remained strong under President Rodrigo Duterte, who took office in May 2016 and has made headlines with his aggressive war on drugs.

Recent attacks on tourist targets in the Philippines, often involving kidnappings, have typically been concentrated in the southern region of Mindanao, which is home to Islamic militant groups. More than 100 people have been killed recently in one Mindanao city, where fighters affiliated with ISIS have been engaging in violent clashes with government forces.

Attacks on tourist areas have hurt visitor numbers in other countries. A string of terrorist attacks in Turkey have seriously damaged the country's tourism sector. The number of tourists entering the country via airports fell 21% in 2016, according to travel intelligence firm ForwardKeys.

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But some countries' tourism industries have rebounded quickly following violent attacks.

France hosted 56.3 million visitors on overnight stays in the last quarter of 2016, a 3.9% rise compared with the same period the previous year, according to government figures. The recovery followed two difficult years for the sector following a series of extremist attacks.

CNNMoney (Hong Kong)