An apparent gas leak triggered an explosion that largely destroyed a Mexico City apartment building Monday, killing one person and injuring at least 29 more, the mayor said.

The explosion occurred at mid-morning on the capital’s south side, leaving a shattered, windowless facade and crumbling interior walls exposed in the 63-unit building.

Mayor Claudia Sheinbaum inspected the scene. The borough of Benito Juárez said later in a statement that 11 of the injured had been taken to hospitals. One of those later died, the mayor said.

Some 300 people were evacuated from neighboring buildings as a precaution.

The Mexico City prosecutor’s office and experts from other agencies were investigating to determine the source of the gas leak.