The powerful blast raises fears of more attacks in the days before Iraq holds a major political conference on July 31.
The street where the explosion occurred was filled with charred vehicles, pieces of glass and twisted metal -- all covered in blood and human remains. Bodies lay in the middle of the road and under cars, the Associated Press reported. The blast killed all 21 passengers on the minibus and destroyed the vehicle.
An Iraqi Health Ministry official said at least 68 Iraqi civilians were killed and 30 wounded in the attack that occurred shortly after 10 am in Baquba, an often violent town located 40 miles north of Baghdad. The official warned the death toll could rise, with many of those injured receiving shrapnel wounds to the chest.
Witnesses said the bomb targeted men waiting outside the al-Najda police station trying to sign up for the force.
"I saw a car overtake a minibus and it slammed right into the queue of people," Riad Abdul Latif, an internal affairs officer at the police station who was some 100 yards away when the bomb went off, told the BBC.
"These were all innocent Iraqis, there were no Americans," on angry man shouted, according to AP reports.
There were several other incidents across the country on Wednesday.
A mortar or rocket struck a busy street in Baghdad, killing one person and wounding five, witnesses told Reuters. South of Baghdad, seven members of Iraq's security forces, backed by U.S. and Ukrainian troops, died in a gunbattle that killed 35 insurgents, Poland's defense ministry said. No U.S. or Ukrainian forces were wounded or killed.
On Tuesday, a U.S. soldier was killed and three others were injured when a roadside bomb severely damaged their armored Humvee while they patrolled the town of Balad-Ruz, some 40 miles northwest of Baghdad, according to army spokesman Master Sgt. Robert Powell.
Wednesday's violence comes three days before Iraq is scheduled to convene a national conference in which 1,000 delegates will gather in Baghdad to consider the country's future and elect a 100-member National Council to oversee the interim government.
U.S. troops and Iraqi security forces have spent weeks planning the security for the event, widely seen as a vital step towards democracy. They are particularly concerned about suicide car bomb attacks like one that killed the former head of the Iraqi Governing Council earlier this year.
Conference organizer Fouad Massoum said Tuesday he was committed to holding the conference this month and said the credibility of Iraq's new government depended on it.
"Credibility is essential because any delay would be explained in a negative way, especially given that Iraq lived for decades under promises that were never fulfilled," he said.