PHNOM PENH, CAMBODIA -- A massive fire at a Cambodian hotel casino that lasted more than 12 hours killed at least 19 people and injured more than 60, while other victims were apparently not yet accounted for Thursday. Neighbouring Thailand sent firetrucks and emergency workers to help cope with the crisis in the bustling border town of Poipet.

Some victims were believed to still be under debris or in locked rooms that rescue teams could not immediately access, so the death toll was expected to rise, said Sek Sokhom, head of Banteay Meanchey' province's information department. He said more than 60 people were injured.

The dead and injured comprised people of several nationalities, including Thai, Chinese, Malaysian, Vietnamese and Cambodian, he said. A local Buddhist temple was being used to receive their bodies.

Videos posted on social media showed people falling from a roof after they were trapped by the fire at the Grand Diamond City casino and hotel in the town of Poipet. Many of those inside, both customers and staff, were from neighboring Thailand.

In a video posted by Cambodia's firefighting agency, onlookers could be heard shouting pleas to rescue people trapped on the roof of the hotel complex, which is more than a dozen stories tall at its highest point. The video showed at least one man falling as the flames reached the roof.

"Oh, please help rescue them. Pump water, pump water!" shouted the onlookers.

The Department of Fire Prevention, Extinguishing and Rescue posted that calls for help were heard from the 13th, 14th and 15th floors at 4 a.m. and hands were seen waving from windows as well as a mobile phone's flashlight signaling from inside the complex.

"The fire was massive, and was inside the casino, so it was difficult for our water cannons to reach it," observed a firefighter on the video posted online by the fire department. He said that was the reason the fire continued burning for such a long time.

The blaze, which started around midnight Wednesday, was finally put out at 2 p.m. Thursday, said Sek Sokhom, adding that the rescue operation was continuing.

He also said an initial investigation found that the fire may have been caused by an overload due to New Year's decorations drawing increased electricity, causing wires to overheat and burn.

Banteay Meanchey police chief Sithi Loh said earlier that 360 emergency personnel and 11 firetrucks had been sent to the scene of the fire, whose cause was not yet known.

"Right now, we are trying to bring the dead bodies from the building down. I don't think there will be any survivors because of very thick smoke. Even we all (the rescue staff) have to wear proper gear when we go inside the building, otherwise we cannot breathe at all," Montri Khaosa-ard, a staff member of Thailand Ruamkatanyu Foundation, a social welfare organization that sends volunteers to disaster scenes, said Thursday afternoon.

Thai and Cambodian rescue teams worked side by side in Thursday's search of the badly burned premises.

Thailand's public television network, Thai PBS, reported that 50 Thais, both staff and customers, had been trapped inside the casino complex. It reported that Cambodian authorities requested help to deal with the fire from Thailand, which sent five firetrucks and 10 rescue vans.

Poipet in western Cambodia is opposite the city of Aranyaprathet in more affluent Thailand, and there is busy cross-border trade and tourism.

Thai PBS cited reports that Aranyaprathet Hospital's emergency ward was full and other victims had to be sent to other hospitals.

Casinos are illegal in Thailand, but neighboring countries such as Myanmar, Cambodia and Laos host the lucrative industry. Cambodia has an especially active casino industry because the Southeast Asian country is also a popular tourist destination with convenient international connections.

A report received from Soth Kimkolmony, a spokesperson for Cambodia's National Committee for Disaster Management, said the Grand Diamond City casino complex has 500 employees, and had 1,000 customers on Wednesday. It was unclear how many were present when the fire broke out.

The casino is just a few meters (yards) from the border checkpoint with Thailand and popular with customers who make the four-hour drive from the Thai capital, Bangkok.

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Associated Press reporter Chalida Ekvitthayavechnukul in Bangkok contributed to this report.