ALAMEDA -- A man was arrested early Wednesday after a suspicious two-alarm fire at an Alameda apartment complex burned for hours, causing some trapped residents to jump to escape the flames, officials said.

Police arrested 45-year-old David Prado, a resident of the complex on the 3200 block of Briggs Avenue, on suspicion of arson, Alameda police Lt. Jill Ottaviano said.

Prado admitted to starting the fire in a police interview, but his motive was not yet known, Ottaviano said.

He was taken into custody after firefighters rescued him from a second-floor balcony at the four-unit apartment building, according to the Alameda fire department.

Fire crews responded to the blaze about 2:50 a.m., and arriving units said the second floor and roof were heavily involved in fire, officials said. Some residents jumped to safety, though none were injured, according to the fire department.

A firefighter suffered a nonlife-threatening injury and was taken to Alameda Hospital. He was released later the same morning.

Some victims wrapped in blankets provided by the Red Cross remained at the scene hours after crews declared the blaze under control at 5:06 a.m. They declined to comment about what happened, however. Seven people lived in the two-story building.

Police and fire officials are investigating the cause of the fire, which caused an estimated $800,000 in damages to the building and its contents, officials said.

"I am the one who started it, I take full responsibility," Prado told KGO-TV at the scene shortly before police arrested him on suspicion of arson. "I am not crazy. They basically tried to make me think I was crazy."

Ottaviano declined to comment on what prompted Prado to allegedly start the fire, which was confined to the apartment building, as well as what was used to ignite the blaze.

Alameda police took Prado into custody on a psychiatric hold on Sunday, Ottaviano said. Neighbors also reported that he was acting erratically over the past several days.

The fire on Briggs Avenue came just a day after fire that began in a floor furnace of a Victorian residence on Bay Street caused about $7,000 in damage, firefighters said.

While the fire was confined to the furnace and the nearby area and caused smoke to spread throughout the two-story dwelling in the 1700 block of the street. No one was hurt.

Peter Hegarty contributed to this report.