Authorities were investigating the exact cause of the explosion, focusing on natural gas accumulation or boiler malfunction as the most probable causes. Foul play has not been ruled out but is considered unlikely, fire Capt. Bryce Blair said.
Fire officials have identified the injured as Marcia Ali, 68, Dennise Rankin, 57, and Joe Matthews, whose age was unavailable.
They were taken to St. Vincent Mercy Medical Center shortly before 2 a.m., and their conditions were not immediately available.
Sheryl Watson and a man authorities identified as Joe Magn were taken to Toledo Hospital. Ms. Watson was released, a hospital spokesman said.
None of them was injured directly by the explosion. They were taken to the hospital for preexisting conditions exacerbated by the explosion. No fire was reported though light smoke was visible.
Several streets surrounding the site of the explosion are closed this morning including Superior and St. Clair streets and Adams Street.
Resident Woodrow Dodge, 70, said he was asleep in his apartment when the explosion shook him awake.
Alarms began sounding and police entered the building to wake residents who were not already roused by the explosion, he said.
The explosion in the basement was reported about 1:30 a.m., setting off alarms inside the four-story building that houses the theater and apartments on three floors above.
A second alarm was dispatched moments after the first crews arrived at the scene.
Another resident said he was about to go to bed in his third-floor apartment when he heard the boom and felt the vibration.
I thought it was something going on in the Valentine Theater, said Ray Patrick, 73, a third-floor resident, explaining that some performances can be heard in the apartments.
He said he looked at the clock and realized it was too late for that.
I heard the alarms going off and I knew I had to get out of there and on down to the street, Mr. Patrick said.
The lower walls and facade were knocked out and debris and glass littered the front of the building at 419 North St. Clair St.
Emergency lights reflecting off the glass-coated street glittered on North St. Clair Street as residents were evacuated by police and firefighters. Some were carried by firefighters to the ground floor and several elderly people in wheelchairs were pushed across the street to the shelter in the basement of Four SeaGate.
Chunks of stone, wood, and drywall were hurled across the street.
A TARTA bus was stationed to provide shelter from the 27 degree temperature. The local Red Cross was notified.
Fire commanders called for assistance with structural collapse expertise.
Toledo Fire Department sent at least nine engines and three trucks.
The 1895-era theater closed in the mid-1970s. In the early 1980s, a community group rallied to save the historic building from the wrecking ball.
The $26 million project was completed in the fall of 1999 and includes apartments and an assisted living on the second floor. Much of the first floor is devoted to common areas for residents and offices for arts organizations.
Apartment Manager Troy Alexander said the residential area has about 50 residents.
I had been here earlier serving Thanksgiving dinner, she said, adding that she was heartbroken over the incident.
An emergency crew from Columbia Gas was at the scene taking readings. Nearby sewers were checked for natural gas, although fire crews later reported finding none.
Blade staff writers Jane Schmucker, Laren Weber, and Mike Sigov contributed to this report.