Major General Sithi Loh, the provincial police commissioner for Banteay Meanchey, confirmed the preliminary number of casualties.
The blaze at the Grand Diamond City hotel-casino in Poipet, on the border of Thailand, broke out late Wednesday night at around 11:30 p.m. local time (1630 GMT/UTC) and was still burning on Thursday morning, Cambodian police said.
The fire started on the ground level but swiftly spread through the multi-story structure, a volunteer with the Thai rescue organization Ruamkatanyu Foundation said.
Around 400 people, including foreign nationals, were believed to be working at the venue, AFP news agency reported.
Cambodia requests Thailand for assistance
Following a request for assistance from Cambodian authorities, Thailand provided 10 rescue vehicles and five firetrucks.
Fifty Thai nationals, including both employees and patrons, were reportedly trapped within the complex, according to Thai PBS, Thailand's public television channel.
The Thai Foreign Ministry said the injured were sent to hospitals in the Sa Kaeo region of Thailand.
Parinya Phothisat, the governor of Sa Kaeo province, said 32 Thais were being treated in hospitals there and one had died.
