The pastor of the Spanish Christian church located on the ground floor of one of the buildings said some of the congregants had been in the church at the time of the explosion, de Blasio said.
More than 250 firefighters working at the scene to battle the blaze, bringing in dozens of pieces of equipment to clear the rubble.
The Department of Buildings says it has issued full vacate orders to several buildings near the blast site because of firefighting operations, but that they believe the surrounding buildings are structurally sound.
A temporary shelter at a school has been set up at for the Red Cross at PS 57 on 115th and Lexington.
Roughly 100 displaced people and dozens of others inquiring about the whereabouts of family members sought shelter at the school, said Red Cross spokesperson Jamie Dierking.
Residents in the area this morning posted pictures of what remained of the buildings on social media.
All Metro-North train service was temporarily suspended because all Metro-North trains in and out of New York City use the rail lines adjacent to blast zone, said Metropolitan Transportation Authority spokesman Adam Lisberg. All service to and from Grand Central Terminal has since been restored. Services on the New Haven and Harlem line and Hudson Line were also restored this afternoon. Subway service was not affected.
Alex Morrell said he was in his home nearby on 116th and Park Ave. when the explosion shook the neighborhood. He said he was one of the first people on the scene before firefighters arrived.
“You heard this deafening explosion and the building shook. [The weather] was finally nice out so we had the windows open and we saw people started spilling into the street,” Morrell said. “It’s New York City, you hear weird noises all the time, then I started hear someone screaming ‘Dear Jesus! dear Jesus!'"
“An enormous crowd gathered. People were walking toward it and walking away with tears in their eyes. It was extraordinarily emotional,” Morrell said.
ABC News' Dan Childs and Ryan Smith contributed to this report.