BAGHDAD – An explosives-laden sewage truck blew up near a police station and a car bomb struck an Iraqi army checkpoint Tuesday – attacks that bore the hallmarks of al-Qaida and showed extremists can still hit hard despite recent gains by U.S.-led forces.

A U.S. military spokesman said the terror network is on the run in some areas, but it “obviously remains very lethal.”

The bombings and a series of shootings mainly targeted Iraqi security forces and tribal leaders facing internal rivalries, but bystanders also were struck. At least 25 people were killed or found dead nationwide.

The deadliest attack occurred when a car blew up near a gas station across the street from an Iraqi army checkpoint, killing four civilians and two Iraqi soldiers and wounding 25 others.

Flames shot out from a military pickup as ambulances raced to the scene, driving past a long concrete barrier that recently was decorated with murals by local artists in an attempt to beautify the city.

It was the latest in a series of car bombings in the capital despite stringent security measures put in place as part of a U.S.-Iraqi military operation – now in its ninth month – and celebrations marking the end of the Islamic holy month of Ramadan.

In the northern city of Mosul, a suicide bomber in a sewage pump truck detonated his payload as he approached a police station recently rebuilt after four previous attacks, police said.

The blast collapsed most of the building, killing at least four policemen, including the station chief, and wounding 75 people, police said. A police spokesman, Brig. Gen. Mohammed al-Waqqa, said several nearby shops and cars were damaged.

Mosul, 225 miles northwest of Baghdad, has seen a rise in violence that many blame in part on an influx of militants who fled the Baghdad security crackdown.

Nobody claimed responsibility for the attacks, but both bombings bore the hallmarks of Sunni Arab insurgents, particularly al-Qaida in Iraq. The terror group had promised to step up attacks during Ramadan, which ended over the weekend with the Eid al-Fitr holiday.