A fire ripped through an office building in Indonesia's capital, Jakarta, on Tuesday, killing at least 22 people, including a pregnant woman, police said.

Flames engulfed the seven-story building, sending thick black smoke billowing into the sky and causing panic among nearby residents and workers in a neighborhood in Central Jakarta.

The fire, which broke out around midday, is believed to have started on the first floor of the building in the Kemayoran neighborhood before spreading to other floors, Central Jakarta police chief Susatyo Purnomo Condro said.

Hundreds of personnel and 29 fire trucks were deployed to try to contain the blaze.

The cause of the fire is still under investigation.

Many workers in the building, which was used as a sales and storage office for a drone company, were out for lunch when a battery started sparking in a storage and testing area, said Condro, citing several witnesses.

The fire was extinguished after three hours of intense effort.

At least 22 bodies — seven men and 15 women, including a pregnant woman — were recovered from the building and taken to the police hospital in East Jakarta for identification.

Television reports showed the tense evacuation of more than a dozen trapped workers, including many women, from the sixth floor using an emergency ladder extended by firefighters.

Each person had to be lowered one-by-one from the building, and several struggled to breathe due to the thick smoke while waiting for their turn.

Families anxiously awaited news at hospitals or near the building rented by PT Terra Drone Indonesia, a company that provides unmanned aerial vehicle technology for various industrial sectors such as construction, mining, oil and gas, energy, plantations and urban planning.