A "very large quantity" of the hallucinogenic drug PCP, with a street value of "at least $3 million" was seized yesterday in a raid at a farmhouse near Easton on the Eastern Shore Maryland State Police reported.

Police said they also raided the Atlantic Glass Co. in Easton, where they seized chemicals, glassware, packaging materials and cookers, and arrested four persons.

State Police spokesman Bill Clark said the glass company apparently was being used as a warehouse for supplies needed in the manufacture of PCP. The actual manufacturing and packaging took place at the farmhouse, he said.

The suspects were identified as Alfred D. MacKown Jr., 32, of Severna park; Edwin L. Talbot Jr., 30, of Arnold; John E. Roe, 25, of St. Milchaels, and High H. Baldwin Jr., 25, of Chestertown. Clark said MacKown owned the farmhouse and was a co-owner of the glass company.

All four were charged with manufacture of PCP and possession with intent to distribute PCP, Clark said.

PCP, known to chemists as phencyclidine and known on the streets as "angel dust", is a legitimate animal tranquilizer that has come into widespread underground use as a producer of hallucinations in humans.

Clark said yesterday's raids followed a two-month investigation that involved several Maryland police departments and the U.S. Drug Enforcement Administration.