Abuja, Nigeria -- A powerful explosion rocked police headquarters in the Nigerian capital of Abuja, a spokesman at the National Emergency Management Agency said Thursday.

No casualty figures were immediately available but several people were injured and cars in the parking lot were destroyed.

"It's serious, very serious, as so many cars are on fire," said Umar Mariga, the National Red Cross spokesman.

Yushau Shuaib, the spokesman for the emergency agency, said a suicide bomber died in the incident but few details were immediately available.

"I saw thick black smoke billowing up from the central area in Abuja," said Jo Abuku, who was driving past the area.

The agency mobilized response units to the police scene, close to the Hilton hotel in central Abuja.

It was unclear who was responsible for the blast. However, the Islamist group Boko Haram has been targeting police and the government in attacks recently.

A pair of explosive attacks at a police station and a church in northeast Nigeria killed 11 people June 8.

Gunmen suspected to be Boko Haram attacked the Gwange police station with explosives.

The militant Islamist group has challenged Nigeria's government. It is regarded as a fringe group in northern Nigeria and is opposed by the Muslim establishment in the country.