Armed robberies were reported at four San Fernando Valley 7-Eleven stores within a span of two hours early Friday morning, the Los Angeles Police Department said.

In each case, two people clad in black or wearing masks walked in and pointed guns at the clerks, according to police. It’s unclear whether the robberies are connected or whether the same people were at the different stores. Police said the suspects in three of the robberies were described as male and were in their late teens or early 20s. One of the robberies involved a woman, according to LAPD. However, police later said they police at least one of the robberies involved two female suspects. The first robbery was reported at 12:45 a.m. at a 7-Eleven store on 17200 block of Vanowen Street in Van Nuys. The robbers got away with an unknown amount of cash in a charcoal-colored Prius, police said.

About half an hour later, another robbery was reported at the store on 8707 Corbin Avenue in Northridge, where two men with a semi-automatic gun got away on foot with money and items from the store, according to LAPD. Surveillance video from the store shows two hooded men walking in and demanding that the clerk opens up the cash registers. They both had bandanas covering their faces. “Open them up,” one of the men says before pulling out a firearm. He then leans over the counter and grabs handfuls of cash from the register before the two leave the store. Another incident followed at 1:30 a.m. at a store on 20871 Lassen Street in Chatsworth, where two men with black masks attempted to rob the store but left empty-handed, police said. The last robbery took place at about 2 a.m. at 16159 Devonshire Street in Granada Hills, where two women in black masks walked in with a semi-automatic gun. One of the women is believed to be between 25-30 years old and had a cast on her left arm, according to LAPD. Police previously said that last robbery involved a man and woman before changing the suspect description to two women. No further details were available.