Two robbers dressed as police officers held up a pharmaceutical delivery truck Thursday and kidnapped the driver before stealing its entire cargo of drugs, police said.

The truck was making an early-morning delivery to a Rite Aid in the San Fernando Valley when two men brandishing semiautomatic handguns approached the driver, Los Angeles police Sgt. Mitzi Grasso said. They were wearing dark clothing with "Police" emblazoned across the back.

"They must have planned it," Grasso said. "They obviously knew the delivery schedule because they were waiting."

One of the men got into the truck with the driver, and they drove to a spot about two miles away, where the driver was ordered out. He was unharmed.

The other suspect had followed in a Honda Accord. Police later found the truck about five miles away in a liquor store parking lot. The men remained at large.

Grasso said the truck was making its first delivery of the day and was filled with a range of drugs, including narcotics such as Vicodin and OxyContin. The robbers made off with everything.

"It was completely cleaned out," Grasso said. "They must have had people standing by."