Baghdad, Iraq (CNN) -- Al Qaeda in Iraq has claimed responsibility for the suicide attack on a recruitment center that killed 48 people earlier in the week.
The group acknowledged its role Friday in a statement posted on a website that frequently carries messages by al Qaeda.
CNN was not able to independently verify the authenticity of the message.
The group said one of its "heroes" targeted a "group of Shiite infidels and apostates who sold their faith for money in order to be a cheap tool used to launch war against Sunni Muslims," the statement said.
The attack took place Tuesday at a center in central Baghdad when a suicide bomber detonated his explosives-laden vest. In addition to the fatalities, more than 120 others were wounded.
The attack took place on the final day of a weeklong recruitment drive and a large number of recruits had been waiting to sign up when the attack occurred, officials said.
The Iraqi government has been pushing to increase security ahead of a U.S. troop drawdown, which would leave a residual American force of 50,000 troops focused on stability operations as well as advising and assisting Iraqi security forces.
Recruitment centers for Iraqi security forces have frequently been targeted by suicide bombers. A recent campaign of bombings and shootings has targeted Iraqi forces, especially in the capital, where gunmen have attacked traffic police and attacked checkpoints, killing Iraqi troops.
Also Friday, gunmen wielding pistols equipped with silencers fatally shot a lieutenant colonel working with Iraq's Interior Ministry in central Baghdad, Iraq's Interior Ministry officials told CNN.
The victim was driving a car with his wife and children when the gunmen intercepted the car and shot him, leaving his family screaming, the officials said.
The family was unharmed, police said.
In the past few weeks, gunmen using pistols equipped with silencers have assassinated many Iraqi security forces and government officials.
Elsewhere Friday, two civilians were killed and another was wounded when a roadside bomb hit a civilian car in the Al-Dora district in southern Baghdad.
Many Iraqis have blamed the recent wave of violence on the current political paralysis, in which quarreling parties have failed to form a government nearly six months after parliamentary elections.
The attack has increased concerns among Iraqis about the ability of security forces to protect them when they cannot protect a government office.
CNN's Mohammed Tawfeeq contributed to this story.