Story by the Associated Press/Curated by Erica Ritz

CAIRO (AP) — A suicide car bomber is suspected to have been behind the deadly explosion that targeted police headquarters in a Nile Delta city, an Egyptian security official said Wednesday as the death toll from the attack the previous day rose to 16.

The explosion in Mansoura, 110 kilometers (70 miles) north of Cairo, was the deadliest bombing yet in a months-long wave of violence blamed on Islamic militants.

The blast was so powerful, it collapsed an entire section and side wall of the five-floor building, incinerating dozens of cars outside and damaging several nearby buildings. More than 100 people were wounded.

Although there was no immediate claim of responsibility, hours after Tuesday’s blast Egypt’s interim government blamed the Muslim Brotherhood, the country’s largest Islamist group — and the organization from which ousted President Mohammed Morsi hails. The attack took place as top security officials were meeting in the Mansoura headquarters to work out arrangements for the Jan. 14-15 constitutional referendum.

The vote is a key step in the country’s political transition after the military’s ouster of Morsi in July, but it has further stoked political tensions, with Morsi’s Brotherhood protesting against the new charter. His group has also staged continued protests since the July coup, demanding Morsi’s release from jail and reinstatement.

According to the security official, the investigation into the Mansoura attack has shown that a bomber drove a pickup truck laden with explosives close to the police headquarters, then detonated it.

Egypts Government Blames Muslim Brotherhood for Deadly Car Bomb Attack

An Egyptian man stands amidst debris car at the site of a powerful car bomb explosion in the Egyptian city of Mansura, North of Cairo, on December 24, 2013. (Photo: AFP/Getty Images)

The official, who spoke on condition of anonymity because he was not authorized to discuss the investigation with the media, provided no further details on the suspected suicide bomber.

But he said that Cairo airport authorities arrested a Brotherhood member late Tuesday on suspicions that he was linked to the attack.

The suspect — identified as 22-year-old Adel Younis Rashid who runs a computer shop in Mansoura — was taken into custody as he was trying to fly to Turkey with his mother and a friend.

The suspect is the son of a leading Brotherhood member and former lawmaker from Mansoura, the official said, adding that authorities have also confiscated Rashid’s computers and telephones.

Earlier, senior Egyptian military and security officials said the Mansoura attack carried the fingerprints of Ansar Beit al-Maqdis, or the Champions of Jerusalem, which has emerged as the main Sinai-based militant group that has staged attacks against Egyptian troops.

Egypts Government Blames Muslim Brotherhood for Deadly Car Bomb Attack

A picture taken in the early hours of December 24, 2013 shows destruction in the Egyptian city of Mansura, North of Cairo, following a powerful explosion. (Photo: AFP/Getty Images)

The group has claimed most of the major attacks in the volatile Sinai Peninsula and the Suez Canal-area cities recent months, as well as a failed attempt to assassinate the interior minister in Cairo in September.

In one of its video messages posted online in October, the group said it was retaliating for the security forces’ ruthless attacks on Islamists, a reference to the crackdown on Brotherhood members and Morsi’s supporters, which has claimed hundreds of lives.

On Monday, Ansar Beit al-Maqdis came out with a message threatening more attacks against Egyptian troops, saying it considers them to be infidels because they answer to the secular-leaning military-backed government.

Also Wednesday, Egyptian state TV reported that of the wounded from the Mansoura bombing had died, bringing the total death toll to 15.

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