DHAKA: An explosion rocked a parking lot at a crowded plaza in Nigeria's capital, killing 21 people and injuring 17 others, authorities said.

The blast happened about 4pm Wednesday in Abuja's "ever-busy Emab Plaza ... at the peak of business," said Ezekiel Manzo, spokesman for Nigeria's National Emergency Management Agency.

About 40 vehicles were destroyed, in addition to the human toll, he said. In a news release posted online, the Nigerian national police force said the injured were being treated at five hospitals.

It was not immediately clear who was responsible for this attack, reports CNN.

Ibrahim Abdullahi told CNN he was in a nearby office when he heard a "loud and terrifying sound."

"When I looked from the window of my office, I saw thick, black smoke enveloped the sky," Abdullahi said. "I could see the raging fire from the blast."

Olumide Sanya said the blast shook the nearby building that he was in. "Windows, doors were shattered."

The area was evacuated and security personnel managed to take control of the scene, according to Manzo.

BDST: 0931 HRS, JUN 26, 2014