Updated

BAGHDAD — A homicide bomber driving a minibus blew himself up in front of the Baghdad office of a popular Arabic news station early Monday, killing six people, and burying a lawmaker alive under the rubble of his collapsed home, police and hospital officials said.

The attack at the offices of the pan-Arab newschannel Al-Arabiya reflects the still dangerous conditions under which many journalists, both Iraqi and foreign, are operating.

The fact that the bomber was also able to make it through not one but two checkpoints before exploding, casts doubt on the abilities of Iraq's security forces as U.S. forces prepare to pull out by the end of August.

The bomber was apparently waved through two army checkpoints leading to the station's office along a narrow street after security guards checked his identification, said Iraqi military spokesman Maj. Gen. Qassim al-Moussawi. The explosion occurred about 10 minutes after the bomber cleared the second checkpoint.

"This has the clear fingerprints of Al Qaeda," al-Moussawi told the channel. No one has yet claimed responsbility for the blast, but al-Moussawi said documents had been found indicating Al Qaeda was planning to target Arabic news channels and other media offices in the country.

Members of the channel's security department were arrested, al-Moussawi added without elaborating.

A neighbor who lived next door questioned how the bomber could have gotten so close.

"What can we say? There are checkpoints. What are they doing?" said the man, whose shirt was speckled with blood. He declined to give his name fearing retaliation, but said many members of his family were injured in the attack.

The roofs of both carswere caved in and a large pink stuffed rabbit was laying on the ground along with pieces of glass and twisted metal.

The massive blast blew out windows in the two-story Al-Arabiya building and left much of the interior in shambles, with doors hanging off their frames. The street outside was littered with the smoldering hulks of at least nine cars, including one that appeared to have been hurled by the explosion on top of another vehicle.

Three guards, a driver, a passer-by and a 50-year-old cleaner died in the blast in front of the building, police and hospital officials said. The attack also wounded 16 people, including former deputy prime minister Salam al-Zubaie, who lives nearby.

The officials spoke on condition of anonymity because they were not authorized to brief the media.

Al-Zubaie, a member of parliament representing the Iraqiya list headed by former Prime Minister Ayad Allawi, was rescued from under the rubble of his home and underwent surgery, said Izzuldin al-Samarraie, an official in the lawmaker's office.

Iraqiya is locked in a tough battle with Prime Minister Nouri al-Maliki to see who will be the country's next leader. Allawi himself came to the scene to inspect the damage.

Al-Zubaie has already survived one attack after he was wounded in the abdomen in 2007 after a homicide bomber concealed among worshippers blew himself up in his home.

"These evil people are targeting the voice of al-Arabiya as well as political figures. They target all Iraq," said government spokesman Ali al-Dabbagh, speaking on the channel.

Iraq has been without new leadership since the March 7 elections failed to produce a clear winner. As politicians bicker, many Iraqis worry that the insurgents are trying to incite more violence in the midst of the power vacuum.

Al-Arabiya is among the most popular Arabic news stations. But militants view it as pro-Western, and its journalists have been singled out for violence in the past. Two years ago, the television's Baghdad bureau manager escaped assassination when a bomb was found under the seat of his car.

One of the station's correspondents, Atwar Bahjat, was snatched from a crowd along with her cameraman and technician while reporting on the 2006 bombing of a Shiite shrine in Samarra. Their bodies were found the next day.

Attacks on journalists had been common during the height of Iraq's insurgency in 2006 and 2007, but have tapered off amid improving security over the past couple of years.

According to the Committee to Protect Journalists, at least 142 journalists and media workers have been killed since March 2003.

In other violence, a bomb loaded with nails and hidden in a pile of garbage exploded in northern town of Beiji, killing three people, hospital officials said.

The Associated Press contributed to this report