At least five people died and 51 were injured in an explosion inside a 10-story apartment building in the central Argentine city of Rosario, authorities said.

The health minister for Santa Fe province, Miguel Angel Cappiello, confirmed the death toll and said that the injured are being treated at four different hospitals around the city.

Investigators are evaluating whether it was a gas leak - as several neighbors claimed - or the rupture of a boiler in the building that caused the blast.

Authorities ordered the gas service to be cut off in the area around the building to prevent additional explosions.

Rescue teams continue working to reach people who remain trapped inside the building, which is in danger of collapsing, police told the state-run Telam news agency.

The rescue work is focusing in the basement, and given that there are a number of injured people in the ruins authorities are not ruling out a possible rise in the death toll.

The explosion occurred about 9:40 a.m. and could be heard more than 40 blocks away, witnesses said. The shockwave from the blast caused damage to neighboring buildings. EFE