A car bomb has killed 14 people and injured 120 as it tore through a police headquarters in the Delta region city of Mansoura, Egyptian officials have said.

Al Jazeera's Peter Greste, reporting from Cairo, said it was not yet clear whether he bomb that rocked Dakhalya Police Security Directorate in the capital of Dakhalya Governorate early on Tuesday had been operated by a suicide bomber or whether it was remotely detonated.

"Police also said that there was a second device," our correspondent said.

The Ministry of Interior said that a police van containing 15 policemen parked by the building was destroyed, set ablaze and four bodies had been pulled out. Rescuers were still trying to reach the other bodies.

Al Jazeera's Mohamed Fahmy said five high-ranking police officers were among those to die in the blast while the head of security and the head of investigations department were critically injured.

"The explosion was so strong that parts of the gate surrounding the directorate is demolished," Fahmy said.

"The injured are both police and civilians.

"Rescue teams pulling people from under rubble."

Egypt referendum

No group has claimed responsibility for the attack, but Fahmy said the initial information indicated that the perpetrators appeared to have inside information about who was in attendance at the meeting in the building.

Parts of the five story building had also collapsed. Fahmy said that police had evacuated many of the surrounding buildings fearing its collapse.

The bombing comes weeks before Egypt holds a referendum on a new constitution that is billed by the country's military-installed authorities as the first step towards democratic rule after the army ousted president Mohamed Morsi in July.

Omar al-Shawatsi, the governor of Dakhalya, of which Mansoura is the capital, told state media the casualties were from the police.

"The explosion was caused by a car bomb," Shawatsi said.

The impact of the explosion was felt around 20 kilometres away and shattered windows of nearby buildings, security sources said.

The head of the security for Daqahleya, Sami El-Mihi, was wounded in the blast and two of his aides were killed, security sources said.

PHOTO CAPTION

Nearby buildings have been damaged in the blast, which was felt about 20 kilometers away [Reuters]

Aljazeera