A 37-year-old man has died during a siege at a hotel in Perth's central business district.

Police say a disturbance began around 2:00am (AWST) when a man on the 12th floor of the Novotel Langley Hotel barricaded himself in his room.

The man lit a fire and hotel staff and police were called to the top floor.

Thick smoke forced an evacuation from the floor and the police tactical response group was called to the hotel on Adelaide Terrace.

Due to concerns about the smoke and uncertainty about whether the man was alone or had a hostage, police entered the room by force.

Inspector Bill Munnee says one officer fired three non-lethal rounds, believed to be bean-bag bullets, but it appears he jumped out of the window.

Police say they tried to negotiate with the man for hours before storming his room.

A witness says the man appeared highly agitated.

"I saw a bloke on about the top floor of the Novotel, throwing lit-up merchandise from the hotel out the window, bedding and chairs," he said.

"About 20 minutes after he did that, I heard him say 'no, no, no' and the next minute the police went in, three shots were fired, and then he came out the window."

Police say the man was known to them.

Both the Coroner and Corruption and Crime Commission will investigate the incident to determine whether the level of force shown by police was justified, and if the man accidentally fell or jumped.