A purported street gang member from Los Angeles was arrested Wednesday in Clearlake after running a stop sign in a stolen Cadillac, Clearlake police said.

Sergio Alvarado, 26, was apprehended in a "high-risk traffic stop" at the intersection of Olympic and Garfield drives after leading Officer Michael Carpenter on a 1-mile chase through residential neigborhoods, Sgt. R.N. Joseph said in a news release.

Carpenter's police dog, Dex, helped police locate several pounds of marijuana and some concentrated cannabis in the Cadillac, which was reported stolen from San Francisco, Joseph said.

A "significant quantity" of the prescription drug clonazepam, an anti-anxiety medication, was found in the trunk, and several hundred rounds of ammunition were found throughout the vehicle, he said.

Alvarado, a convicted felon who has served time in state prison, was held on suspicion of evading police, possession of stolen property, possession of ammunition by a prohibited person and possession and transportation of marijuana.

At the Lake County Jail, officials found about 100 doses of Xanax, another anti-anxiety drug, in Alvarado's rectum, Joseph said.

Alvarado claimed to be a sure? gang member from Los Angeles, police said. He was held at the Lake County Jail on $15,000 bail.

Chelsea Lynn Dawson, 22, of Clearlake, a passenger in the Cadillac, was arrested on a felony narcotics warrant from Los Angeles, Joseph said.

Dawson was held on $30,000 bail.