A lithium-ion battery exploded in a city sanitation truck in Midtown Friday morning, triggering panicked 911 calls from people who heard the blast, officials said.

The small explosion occurred about 8:05 a.m. after garbage men tossed a duct taped box into their truck during trash pickup on East 31st Street near Fifth Avenue.

When the workers cycled the truck – the process where the compactor crushes the waste – the box ignited and exploded, according to a Department of Sanitation spokeswoman.

People within earshot called 911 to report the blast, the FDNY said.

The sanitation workers were able to reverse the cycle and throw the box into a nearby puddle, extinguishing the fire.

Authorities later determined the blast was sparked by a lithium-ion battery inside the box, which wasn’t immediately identified.

Soon after the scare, the truck resumed its normal operations. Nobody was injured.