EL CAJON, Calif. -- El Cajon police this week seized more than 8,700 glass pipes from local smoke shops and arrested three shop owners on suspicion of possessing illegal drug paraphernalia, it was reported Friday.

Authorities are planning to arrest a fourth shop owner after discovering the tubular pipes, which police say are used for smoking crack and methamphetamine, The San Diego Union-Tribune reported.

The bust, which netted at least $43,500 worth of goods, was part of a larger, countywide effort to confiscate illegal drug paraphernalia from businesses.

The campaign is being coordinated through the county Methamphetamine Strike Force and the county District Attorney's Office, the newspaper reported.

Hookas, shorter water pipes and ceramic pipes were not targeted.

Teams of officers fanned out across El Cajon on Tuesday, visiting nine of the city's 12 smoke shops. Owners at those nine stores had been warned in hand-delivered letters about six weeks ago that carrying the glass pipes was illegal and that local law enforcement agencies planned to enforce the law, according to the Union-Tribune.

Police told the newspaper they will follow up with the remaining three shops.

Most of the pipes -- more than 8,300 -- were found at a single business, Quick Stop Shop on West Main Street, the Union-Tribune reported.

Similar warning letters have been delivered to shops in Lakeside, Santee and Spring Valley, the newspaper reported.