SAN DIEGO (CBS 8) – Police officers are investigating an armed robbery at a Clairemont-area restaurant overnight, after two gunmen stormed the establishment, tied up employees and fled with cash.

Police said as the Blackthorn Irish Pub and Grub in 3000 block of Clairemont Drive was shutting their doors at 2:00 a.m., two suspects wearing ski masks busted through the rear door.

One suspect had his handgun pointed at the owner and a worker. They were forced to the ground while the second suspect demanded cash from an employee. The two suspects then tied up the victims, which included two men and a woman, as they robbed the business.

"In this particular situation they tied up the employees. They were holding them for an extended amount of time. This gives the suspects an opportunity to ransack the business a little bit longer and increases the chances of something happening between the employees. It increases the danger level,” explained Lt. Jason Weeden with the San Diego Police Department.

As of this report, police do not have descriptions of the suspects. Now, they will examine any available surveillance video and DNA found at the scene.

"Two unknown suspects entered the business and demanded cash from the employees. They used handguns to demand the cash. They tied up the employees and had them face down on the ground, rob them of their possessions and cash from the business and fled out the back door," continued Weeden.

Robbery detectives were also on the scene interviewing the victims early Thursday morning.