A Bensalem Township police officer on routine patrol Sunday with his K-9 dog made one of Bucks County's biggest drug busts, seizing heroin and methamphetamine worth $11.7 million.

The 15 kilos of heroin and 20 pounds of "very pure crystal methamphetamine" were earmarked "for the Delaware Valley," township Public Safety Director Fred Harran said at a news conference Monday.

"I can't imagine how many lives were saved last night of people overdosing on this stuff," Harran said with plastic-wrapped bricks of drugs lined up in front of him. "There's a lot of people not going to get high this week."

The drugs were found after Officer Brian Cowden pulled over a tractor-trailer with California plates on Street Road and his police dog, Edo, sniffed out the narcotics, Harran said.

The driver, Estaban Zalazar Velasco, 35, of Galt, Calif., and passenger, Juan Ledesma-Nolasco, 48, of Livermore, Calif., were arrested and arraigned before District Justice Joanne V. Kline. Each was being held Monday on $1 million bail in Bucks County Prison, on felony charges of criminal conspiracy and the manufacture, delivery, possession, and intent to deliver controlled substances.

Cowden, a 10-year veteran of the force, was on an "unrelated detail" at State Road and American Drive when he saw the two men "walking around suspiciously," Harran said. After they drove off in the 18-wheeler, the officer noticed several vehicle violations and pulled them over.

Edo, a 21/2-year-old Belgian Malinois trained to detect narcotics, sniffed out the heroin and methamphetamine in the truck's sleeping compartment.

The heroin has a street value of $9 million, and the methamphetamine $2.7 million, Harran said. The latter appeared to have come from Mexico, he said. "It's not typical Pennsylvania methamphetamine."

The arrests are "going to put a dent in someone's business," he added.

Police are still investigating where the drugs came from and the route the two suspects took to Bensalem.

In 2009, Cowden received the county's Outstanding Police Performance Award from the Citizens' Crime Commission of the Delaware Valley. He had confiscated more than $500,000 used in illegal narcotics traffic, plus drugs "that were passing through our township for distribution in the Delaware Valley," according to Bensalem's newsletter.

Cowden was not available for comment.