Firefighters respond to an explosion that leveled two apartment buildings in the East Harlem neighborhood of New York, March 12, 2014. Authorities in New York are combing through rubble for signs of life after a gas leak in East Harlem on Tuesday triggered an explosion that caused two buildings to collapse. Several people remain missing after the tragedy that killed at least seven and injured dozens

Firefighters pulled a seventh body from the rubble Thursday morning as the death toll continued to rise from Wednesday’s gas explosion in New York City.

A gas leak triggered the explosion Wednesday morning, which injured more than 60 people and leveled two buildings in upper Manhattan. At least three of the injured were children, the Associated Press reports.

Rescue workers spent a wet, frigid night searching for victims buried under the rubble, using floodlights and thermal imaging cameras to identify heat spots that might indicate bodies. Police in surgical masks guarded the site as temperatures dropped into the 20s, according to the AP. Several people were still missing as of Thursday morning.

A team from the National Transportation Safety Board, which investigates pipeline accidents, arrived at the scene Wednesday evening, and a NTSB investigator said they would conduct a timeline of events and look into how the Con Edison utility handled reports of gas odors, the AP reports.

Residents of one of the buildings told the New York Times that they smelled gas Tuesday night and the odor was still noticeable Wednesday morning.

A Con Ed spokeswoman confirmed that the utility received a call about a heavy gas odor at 9:13 a.m., less than twenty minutes before the explosion. A Con Ed crew dispatched two minutes after the call arrived just after the explosion.

The New York City Fire Department said it had no reports from tenants of gas leaks in the past month.