Santa Rosa police on Wednesday seized three pounds of heroin and arrested two men suspected of selling drugs for a Mexican cartel.

The bust happened as undercover detectives were trailing Armando Hildago Sandoval, 29, of Stockton, who was suspected of supplying heroin to a Santa Rosa dealer, Sgt. Rich Celli said.

He was followed to an apartment on Timothy Road, across from Roseland University Prep High School, where he got out and returned to his car a short time later, Celli said.

He was pulled over after he left and found to be in possession of $20,000 cash, the sergeant said.

About that time, detectives saw another man leave the apartment and throw a large plastic bag onto a porch after noticing police cars, Celli said.

Gerardo Robles Vasquez, 47, of Santa Rosa, had three-quarters of a pound of heroin with him and a search of the apartment turned up 2-3/4 pounds of the drug, the sergeant said.

The heroin had a street value of between $24,000 and $30,000, Celli said.

The men were booked into Sonoma County jail on drug trafficking charges and several related charges, including allegations of conducting drug sales in a school zone and separate child endangerment counts for having children in close proximity to the drugs.

You can reach Staff Writer Paul Payne at 568-5312 or paul.payne@pressdemocrat.com. On Twitter @ppayne.