SAN LEANDRO — A two-month undercover investigation led police this week to arrest three men and seize more than 500 marijuana plants, eight pounds of processed pot, $45,000 in drug money and two assault rifles that had been made to resemble toy guns.

Following an anonymous tip, detectives targeted two San Leandro homes Wednesday — one in the 14500 block of Maracaibo Road and one in the 2100 block of Marina Boulevard — where marijuana was being grown and guns and cash were kept, police said.

One of the more disturbing discoveries in the Marina Boulevard house were assault rifles apparently made to seem like toy guns, an officer said.

Police at the Marina Boulevard house found two partially assembled AK-47 assault rifles with orange plastic tips on their barrels, making the weapons look like toy guns. The colored tips are put on toy guns that otherwise so resemble real weapons that police have mistaken them for deadly threats.

“It is frightening to know that AK-47 assault rifles capable of penetrating body armor worn by law enforcement officers were made to look like toys,” said San Leandro police spokesman Lt. Robert McManus.

Police said 30-year-old Tony Ho, who was leaving the house when they arrived, also had three AR-15 assault rifles with several parts lacking serial numbers and illegally modified to accept 30-round magazines.

“We are happy that we were able to take five assault rifles out of the hands of someone involved in criminal activity,” McManus said.

Following Ho’s arrest, police raided the home on Maracaibo Road, where they found John Er, 31, and Brian Nguyen, 24, harvesting mature marijuana plants in bedrooms and a garage. Police said they counted 536 marijuana plants, capable of producing 116 pounds of pot, with a street value of about $290,000.

Officers also found $45,556 in cash and another eight pounds of processed marijuana. Police said the suspects had bypassed the house electrical panel, creating a hazard that PG&E technicians were called to fix.

The men were arrested on suspicion of illegally cultivating marijuana for sale and theft of the electrical power at the Maracaibo residence. Ho also was held on suspicion of having the assault weapons.

The men posted $290,000 in bail and were ordered to be in Alameda County Superior Court on Friday afternoon for arraignment.

Follow Kristin J. Bender at Twitter.com/kjbender.