A fast-moving fire tore through an Alameda apartment building before dawn on Wednesday, trapping several residents on the top floor. Within hours, police had a suspect in custody.

Crews were called at about 4:45 a.m. to an apartment complex in the 400 block of Central Avenue. According to the Alameda Fire Department, the first firefighters found heavy flames inside a ground-floor unit. The fire was already spreading into neighboring apartments and cutting off people living on the floors above.

Rescues on the third floor

Firefighters rescued three people who were trapped on the third floor. A fourth person on that floor jumped from the building to get away from the fire and was hurt, the fire department said. Police said an officer found that person behind the complex and got them medical help. KRON4 reported, citing the fire department, that two people in all were taken to the hospital.

About 35 firefighters had the fire under control in less than 20 minutes, officials said. Even so, six units were damaged or destroyed, and about 12 residents were forced out of their homes. The American Red Cross was on scene helping displaced residents with money for a hotel, food and clothing, NBC Bay Area reported, and each household is supposed to get a caseworker for longer-term help.

The arrest

Alameda police arrested a 52-year-old Alameda resident on suspicion of arson and of committing a felony while out on release in an earlier case, according to Bay City News. NBC Bay Area reported that police identified him as Bernard Collins.

Residents of the complex, which they called the Surf Apartments, told NBC Bay Area that Collins lived there. They said police arrested him shortly after the fire started. Neighbors also told the station that he had caused ongoing problems at the complex and had made threats as recently as the night before. Those accounts come from neighbors and have not been confirmed by police. An arrest is not a finding of guilt, and Collins has not been convicted of any crime.

Police said the motive and the circumstances are still under investigation, and fire officials said the fire itself remains under investigation as well.

If you were affected

Displaced residents can get help through the American Red Cross. Anyone who saw what happened on Central Avenue early Wednesday can contact the Alameda Police Department.