Authorities are investigating a robbery at a jewelry store at a outlet mall in northwest Harris County.

The Harris County Precinct 4 Constable's Office says it happened around 9:20 a.m. Wednesday at Zales Outlet located at the Houston Premium Outlets off Hempstead Highway.

Officials said three black men walked into the store and tied up the two female employees with zip ties.

Robert Marshall was coming to do some repair work at the outlet mall Wednesday morning when he saw three robbers run out of Zales. He says they were carrying a gigantic garbage bag and it was full of loot.

"That thing musts have been 100 to 150 pounds at least.  It was a big heavy bag. Then they had another bag that was full, it was so bad the guy had to keep setting it down and picking it up."

Investigators said the suspects robbed the store, cleared out the safe and were gone before police arrived.

Deputies don't know how much jewelry they stole and they say it's unclear how the three robbers got into the store, but they had their faces covered with bandanas when they tied up the two women in the back room.

After a while the women were able to free themselves and dial 911.

"There were three men that were in the store, one occupying a white, Econoline van. That's what they fled in was the white van." Said Lt. Wayne Schultz. "They jumped in and burned out in a matter of seconds."

Officials are still looking for the suspects and the white cargo van. They're also reviewing surveillance footage from inside the store.