Among those injured was a coffee cart vendor, who was hospitalized in stable condition, Metropolitan Transportation Authority spokesman Kevin Ortiz said. He said the vendor was struck by the box truck.
The MTA has not been able to independently confirm that the bus driver was killed, Ortiz said.
Police said there were two passengers on the bus at the time of the crash. They said the truck driver, who also suffered minor injuries, was being questioned at the hospital.
"Apparently a stolen box truck traveling on 7th Avenue struck a M14 bus" at the intersection, Ortiz said. Police did not immediately confirm that the truck was stolen.
Both vehicles careened onto the sidewalk and into scaffolding that collapsed around them before striking a 12-story commercial building at 14th Street and 7th Avenue. Several parked cars were also hit.
Craig Ydolly was on the block facing the other way when he heard the crash. He said it sounded like the scraping sound a snowplow makes. He turned around and saw the scaffolding falling on the truck and the bus and a man lying injured on the ground.
The bus was leaking gas, said Ydolly, who distributes newspapers on that corner.
Jose Cherrez, who lives one block from the scene, said the crash woke him up.
"It sounded like an explosion. I heard the ambulances about 10 minutes later," he said.
Seventh Avenue between 13th & 15th streets and West 14th Street between 6th & 8th avenues were closed following the crash. Local bus service was being rerouted. Subway service was not affected.