A suspicious fire combined with a blocked exit turned the women's ward of a Moscow drug treatment hospital into a deathtrap Saturday as flames and smoke overcame patients. At least 45 women trapped behind a locked gate were killed in the deadliest fire in the Russian capital in decades.

Russia's chief fire inspector, Yuri Nenashev, said he was "90 percent certain" the fire was set deliberately, and Mayor Yuri Luzhkov said it appeared to be arson or extremely careless handling of flammable materials.

The fire erupted in a wooden cabinet in a kitchen at one end of a corridor on the hospital's second floor — a factor that led to suspicions of arson. The main emergency exit was blocked by a locked gate and the only other way out was cut off by choking smoke, Nenashev said. The barred windows were shut with locks that hospital personnel, who had the keys, apparently did not have time to open.

All 45 women were dead by the time firefighters arrived, said Alexander Chupriyan, the deputy emergency situations minister.

"Judging by the placement of the bodies, they really tried to get out," he said.

Televised footage showed the ravaged, peeling walls of a corridor and black ash covering beds and belongings — a teacup, some buns for a snack — in a room that appeared otherwise undamaged. NTV showed a soot-covered survivor sitting outside the building next to the sprawled figures of two women who appeared dead or unconscious.

Moscow fire department spokesman Yevgeny Bobylyov said that investigators were still working at the site of Hospital No. 17 in southern Moscow but that it was already clear that the first call to the fire department — around 1:30 a.m. had come far too long after the fire started.

"Secondly, the hospital personnel worked very badly, they did not take steps to evacuate people in the early stages of the fire," he said.

One hundred sixty people were evacuated from the five-story building, and 10 people were hospitalized with carbon monoxide poisoning, Bobylyov said. Firefighters put out the fire within an hour of the first call for help, he said.

Most victims died of asphyxiation, Bobylyov said; some died of burns, Moscow city prosecutor Yuri Syomin. Russian media reported that two hospital staff members were among the dead.

A psychologist at the hospital, Olga Rudakova, told NTV television many of the women there are HIV-infected drug addicts, and NTV reported that most of the victims were under 35 — some committed by relatives.

The ITAR-Tass news agency said that the area of the fire was comparatively small, some 1,075 square feet, but that the heavy concentration of smoke killed people. Ekho Moskvy radio said burning plastic wall coverings worsened the thick, toxic smoke.

The fire might have started in a pile of discarded materials, Syomin said.

The building, set deep in a courtyard, but no obvious signs of fire or smoke damage on its facade. Hours after the pre-dawn blaze was out, relatives wailed or sobbed softly in televised footage.

Nenashev said fire inspectors had visited the hospital twice, in February and March, and had recommended the temporary closure of the facility after the second visit because of fire safety violations.

Russia records about 18,000 fire deaths a year — roughly 10 times the rate in the United States. Experts say fire fatalities have skyrocketed since the collapse of the Soviet Union, in part because of lower public vigilance and a disregard for safety standards.

It was the deadliest fire in Moscow since a 1977 blaze at the massive Rossiya Hotel near the Kremlin — torn down this year — in which the official death toll of 42 has been questioned.

Emergency response officials ordered all health facilities in the city inspected for fire safety compliance, Russian agencies reported. In November 2003, a pre-dawn fire swept though a dormitory for foreign students who had been quarantined for medical checks, killing 43 and injuring nearly 200. Many were trapped behind permanently locked exits, causing some to leap from the five-story building.