A damaged area is seen after an explosion at a security building in Mansoura city, the capital of Dakahlyia Governorate, about 120 km northeast of Cairo, Dec 24, 2013.[Photo/Agencies]

CAIRO -- At least 14 people were killed and 130 others wounded early Tuesday as a powerful explosion ripped through local police headquarters in Egypt's Nile Delta city of Mansoura, semi-official Ahram newspaper reported on its website.

Three bombs had been planted and two of them went off almost simultaneously. The third one in a car nearby was defused, the website quoted an anonymous security official as saying.

The attack took place at 1: 10 a.m. local time (2310 GMT Monday) at the northern Governorate of Daqahliya, official news agency MENA said, adding that a nearby five-store bank building collapsed and dozens of vehicles were wrecked due to the strong explosion.

Most of the victims were police conscripts, Omar el-Shawatqi, governor of Daqahliya, told reporters. "They have been rushed to nearby hospitals," he said. Mansoura is the capital city of Daqahliya Governorate.

The head of Mansoura's security directorate was among the injured and the death toll is expected to increase, as more people are still trapped inside the building, he added.

State TV footage showed that searches were continuing around the neighboring blocks to make sure if there are still survivors.

There's no shortage in blood, medication or medical equipment at Daqahliya hospitals, MENA quoted a senior Health Ministry official as saying.

Interim Prime Minister Hazem el-Beblawi condemned the attack, saying the bombing was a hideous terrorist attack that aims at threatening the people and the implementation of the transition roadmap. He vowed to punish the attackers severely.

On Tuesday, Beblawi declared Muslim Brotherhood, the country's oldest and most influential Islamist movement, as a terrorist group.

"The Brotherhood has shown its ugly face as a terrorist group and its acts will not weaken the Egyptian people's determination to move forward," Beblawi was quoted by his media adviser Sherif Shawqi as saying.

In October, the Egyptian authorities ordered to remove the Muslim Brotherhood from a government list of accredited non-governmental organizations. Earlier, a Cairo court also ordered to ban all activities of the Brotherhood group, seize its funds and form a panel to administer its assets.

Mansoura witnessed a similar explosion on July 24, when at least 11 people, mostly security personnel, were injured.

Tensions are running high in Egypt since the fall of former Islamist President Mohamed Morsi in early July, with a string of bomb attacks taking place across the country.

The Islamist militants based in the restive northern Sinai Peninsula were blamed for those attacks. The military then launched an offensive to crack down on them.