TACOMA - Hotels along the Interstate 5 corridor in Tacoma are on edge after a string of violent robberies in the past week.

Police say crooks have hit four hotels, and now they're looking for the two men who did it.

The string of robberies began Friday night at the La Quinta Inn, and the robbers' approach has been similar in all of them.

In each crime, one of both of the suspects takes the clerk at the registration by surprise, jumping over the counter and demanding money. The crooks move quickly and threaten to kill the clerks if they don't cooperate.

In the first robbery, at La Quinta Inn, the clerk handed over the cash and tried to run. But seconds later one of the robbers punched her in the face before taking off.

Says Tacoma police detective Larry Andren: "No weapon has been indicated. But in all of these they have made threats that if they didn't cooperate they would kill them."

On Saturday night, one of the two suspects hit a second target - the Extended Stay America near Tacoma Mall.

In that robbery, the crook talked to the clerk, then pretended to pull out his wallet. Suddenly he jumped over the counter, attacked the clerk - then walked off with the cash.

On Sunday night, it was the same story - this time at the Best Western near the Tacoma Dome. The suspect even showed up in the same clothes.

And on Wednesday night he hit the Holiday Inn Express, taking over the cash register as guests walked by.

"We don't know if these people aren't armed," says Andren. "If they run into somebody who is not compliant, what their escalation value is. How far are they going to go to get what they need?"

Tacoma police worry the robbers will hit again - and fear they will become more violent.

They also say the crooks aren't hauling in much from their heists. At one hotel they only got $20.

Anyone who recognizes the robbers from the surveillance photos or the video is asked to call Crimestoppers at (253) 591-5959 with any information they might have.