Eight American soldiers were killed in roadside bombings and a helicopter crash in a restive province north of Baghdad, the military reported Tuesday, making May the deadliest month of the year for U.S. troops in Iraq.

In other violence, three German computer consultants were kidnapped Tuesday from an Iraqi Finance Ministry office in Baghdad, an Iraqi government official said, and two car bombings killed 40 people in the capital, police said.

The Americans, all from Task Force Lightning, were killed Monday in Diyala as the U.S. commemorated Memorial Day, bringing the number of U.S. forces killed this month to at least 110.

The military said six of the soldiers died in explosions near their vehicles and two were killed in the helicopter crash. It was not clear if the helicopter was shot down or suffered mechanical problems.

The Germans were kidnapped by a group of gunmen wearing police commando uniforms who arrived at the ministry office — down the road from the main Finance Ministry building — in a convoy of white sports utility vehicles, which are often used by police, according to the government official and a police officer. Both the men spoke on condition of anonymity because they were not authorized to speak to the media. Police have been accused of involvement in attacks in the past.

Germany’s Foreign Ministry said it was checking the report.

“The embassy in Baghdad and all of the relevant offices have been alerted and are working to swiftly clarify the matter,” the ministry said.

Earlier this year, militants here kidnapped German citizens Hannelore Marianne Krause, and her adult son, Sinan, and threatened to kill them if Germany did not pull its troops from Afghanistan. German officials have not said what the mother and son were doing in Iraq, where they disappeared on Feb. 6. Their fate remains unknown.

In Baghdad, a parked minibus packed with explosives blew up in Tayaran Square, riddling cars with shrapnel, knocking over pushcarts and sending smoke into the sky, witnesses said. The blast killed 23 people and injured 68.

Yousef Qasim, 37, was working in his clothing shop 200 yards away when the blast tore through a line of buses waiting at the square, he said.

“I rushed there to see about four or five burning bodies,” he said.

Shop owners grabbed their wares and tried to flee, fearing a second blast, said Talib Dhirgham, who owns a nearby laundromat. Police who arrived at the scene confiscated the cameras of journalists who came to cover the attack.

More than an hour later, a pickup truck parked in a market for spare car parts exploded in the Amil district in western Baghdad, killing 17 people and wounding 55, police said. The blast damaged 10 nearby houses and a Shiite mosque and set eight cars ablaze, police said.

In other violence, gunmen in Samarra, 60 miles north of Baghdad, set up fake checkpoints on the outskirts of the city and abducted more than 40 people, most of them soldiers, police officers and members of two tribes that had banded together against local insurgents, police said.

The attacks came a day after U.S. and Iranian officials met in Baghdad under the auspices of Iraqi Prime Minister Nouri al-Maliki to try to end the violence here.

Anti-American Shiite cleric Muqtada al-Sadr on Tuesday criticized the talks as interference in Iraq’s internal affairs and warned Iraqi officials not to participate in them.

“I call on the brave people to reject these negotiations,” he said in a statement.

On Monday, 36 people were killed across Baghdad in a wave of attacks. Another 33 bullet-riddled bodies were dead, tortured and abandoned in different parts of the capital, the apparent victims of ongoing sectarian violence.