Four Madison convenience stores were robbed Wednesday, according to statements issued by the Madison Police Department.

Mike Hanson, public information officer for the MPD, said in a press release the investigation remains open.

"It is believed that two individuals, working together, are responsible for these same four convenience-store robberies," Hanson said, adding "no one has been arrested."

The first robbery took place approximately 2:10 a.m. at a Citgo on East Washington Avenue, where the suspect allegedly showed a black handgun to the clerk. Less than three hours later, an Open Pantry on the West Beltline Highway was robbed, but the suspect only implied he had a weapon.

When contacted, Open Pantry employees said they had no knowledge of being robbed Wednesday.

Another robbery took place later that night, when a Clark gas station on South Park Street was robbed about 7:25 p.m. by a suspect who implied he had a handgun.

"They didn't get much of anything," said a Clark employee who spoke on condition on anonymity. "We don't keep that much in the drawer."

The final robbery took place at about 9:45 p.m. at a Citgo station on North Sherman Avenue, where the suspect showed the clerk a black handgun.

If these crimes are connected, the consequences would be worse for the suspects, said Asst. District Attorney Mike Verveer.

"The penalties definitely increase for each and every incident," Verveer said.

Anyone with information related to these robberies is asked to contact the MPD.