There were conflicting reports on the number of killed in Wednesday's blast.
US military in Baghdad said five people were killed and 29 were wounded, many of them Iraqi police. However, doctors in Baquba said only two were killed.
There were also conflicting reports about whether the blast was caused by a car bomb or a bomber.
A policeman at the scene said he saw a car racing towards the police station before exploding. But a US military spokeswoman said explosives in a car were commanded by remote control to detonate.
Resistance fighters have targeted police stations on a number of occasions, as they consider them "collaborators" of the US-led occupation.
Twin car bomb attacks on police stations in Baquba, 65km north of Baghdad, and the nearby town of Khan Bani Saad in November killed at least 16 people and wounded more than 30.
It was also revealed on Wednesday that eight Iraqis were killed on Tuesday in an apparent firefight with US troops near the town of Samarra, north of Baghdad.
US thinks detained men may have
helped al-Duri find safehouses
US military officials accused the Iraqis of opening fire on occupation troops in a "drive-by shooting".
She said 26 alleged attackers were apprehended following the incident and four vehicles were confiscated.
In related developments, gunmen ambushed a convoy operated by a US contractor, killing two drivers and wounding several others.
The convoy, operated by Kellogg, Brown and Root, was ambushed south of Tikrit, said the US military. Nationalities of the victims were not released.
Meanwhile, the US military announced on Wednesday the detention of Khamis Sarhan al-Muhammad, the number 54 on Washington's list of 55 most wanted Iraqis from the ousted government of Saddam Hussein.
Al-Muhammad, who had a $1 million bounty on his head, was seized on 11 January near the restive town of Ramadi, said military sources. Al-Muhammad was chairman of Saddam's Baath party in the holy city of Karbala.
In related news, US forces seized four relatives of Izzat Ibrahim al-Duri, the man most wanted by the US in Iraq, after a pre-dawn raid in central Iraq on Wednesday.
US military police swooped on two homes in the town of Samarra, about 100 km north of Baghdad and a hotbed of anti-occupation attacks, and detained four nephews of the former Saddam loyalist.
Al-Duri is number six on the US military's 55-most-wanted list and carries a $10 million bounty on his head. Following Saddam's capture in December, he is the most wanted man in Iraq.
The US military thinks two of the detained men may have helped to find safehouses for al-Duri, but it would give no further details on the suspects.
US officials believe al-Duri is one of the key coordinators behind the eight-month-old resistance which has killed more than 200 US troops.