Columbia ? Hundreds of leftist rebels bombarded a remote police station with makeshift mortars in a pre-dawn attack Wednesday and ambushed a column of police reinforcements, killing at least 16 officers, authorities said.

The six-hour assault in the village of Tierradentro, 230 miles northwest of Bogota, was the bloodiest since President Alvaro Uribe was re-elected in May in a landslide that endorsed his get-tough policy with the rebels.

Authorities blamed the Revolutionary Armed Forces of Colombia, better known as the FARC. At least 10 police officers were missing and four civilians wounded, said Jairo Lopez, the top security official for Cordoba state, where the attack occurred.

Analysts said the attack was part of a broader campaign by the rebel group.

“This is a nationally coordinated offensive by the FARC,” said political analyst Leon Valencia. “The FARC is looking to reclaim territory that was once held by the (far-right) paramilitaries.”