Don Whittenberg, middle right, puts his arm around Vicksburg Deputy Chief Janelle Lee, right, while talking with attempted bank robbery witnesses this morning outside of the Mutual Credit Union at Waterways Experiment Station. (The Vicksburg Post/PAT SHANNAHAN)

A bank robbery went sour today at Mutual Credit Union’s Waterways branch when four men with ski masks showed up half an hour before the bank opened and a teller refused to let them in.

Vicksburg police then used dogs to track the men through Hamilton Heights subdivision just across Halls Ferry Road from the federal research complex.

Three men were arrested at various locations in the neighborhood and one was still at large at 10 a.m. today, said Police Chief Mitchell Dent. The bank had been scheduled to open at 9.

Police would not release the names of the men who were arrested, but said one, injured scaling the barbed wire fence that surrounds Waterways Experiment Station, was taken to Vicksburg Medical Center.

Police said they found in the bank parking lot a .25-caliber automatic pistol that the suspects may have planned to use in the robbery.

Some Mutual employees thought the men might be cleaning staff when they showed up at the credit union’s door at 8:30 a.m. They were about to open the door when teller Brenda Thompson became suspicious.

“I couldn’t tell if they had a gun or not, but I saw one of them put on a ski mask, and I said Don’t open the door,'” Thompson said. “I’ve never stared a robber in the face before.”

The episode was Vicksburg’s second attempted bank robbery this year.

Clayton Hastings, 51, was arrested March 24 after a robbery at RiverHills Bank in the parking lot of the former Battlefield mall earlier that day.

He was found by FBI agents and police gambling at Ameristar Casino.