Los Angeles police detectives are investigating a robbery at a Northridge marijuana dispensary over the weekend that left an employee in critical condition after he was shot in the face.

The shooting was the second at that business this year and the third medical marijuana dispensary targeted over a three-day period last week. Two people were fatally shot Thursday in pot shop robberies in Echo Park and Hollywood and a third man was wounded.

The Northridge shooting took place shortly after 9 p.m. Saturday at the dispensary in the 8900 block of Reseda Boulevard, police said. The victim, whose name was not released, was taken to Northridge Hospital Medical Center, where he is listed in critical condition. The suspects, who were not immediately identified, made off with approximately $11,000 in cash, police said.

Two defendants are awaiting trial in connection with a January shooting at the store that left a 33-year-old clinic employee wounded during an attempt to steal his wallet.

Los Angeles Police Department detectives said they did not believe there was any connection between the San Fernando Valley case and Thursday's robberies, which occurred hours apart.

"We have no evidence to believe that the three [robberies] are connected," said Kevin McClure, the captain in charge of the Los Angeles Police Department's Robbery-Homicide Division. "But do I think it's a disturbing pattern based on what it is, absolutely."

The robbery at the medical marijuana clinic on Sunset Boulevard in Echo Park left one worker wounded and another dead. The dead man was identified as Matthew Benjamin Butcher, 27, of Los Angeles. The second incident occurred hours later and a few miles away on El Centro Avenue in Hollywood when an unknown number of suspects stormed into the shop. Ila Ali Packman, 39, of Hollywood was killed in that incident.

The killings coincided with a city crackdown on pot businesses that has resulted in the closure of dozens of the outlets.

The city attorney's office recently notified about 400 marijuana dispensaries that they must shut down if they do not meet location restrictions outlined in a new ordinance that took effect this month. The dispensaries were given six months to comply with the law, but many have already closed.