RICHMOND, Va. -- Police are investigating at least three armed robberies that happened between 1 a.m. and 2:30 a.m. Tuesday.

Someone shot a man in the neck around 1 a.m. near the intersection of Cedar Street and N. 22nd Street in Union Hill. The shooting victim, who police said was in his 20's, suffered life-threatening injuries. The shooter took the man's cellphone and credit cards.

About 40 minutes later, on West Marshall Street near Goshen Street, at least two gunmen robbed several people of their iPhones and school books.

Less than an hour later, two other people were robbed outside the 3rd Street Diner on N. 3rd and Main Streets in downtown Richmond. Following that robbery, one of the two robbers fired a warning shot into the air.

"We hear this gunshot, we turn around and this guy's got a gun in the air, and I was like 'yeah that's a gun, go that way, back up," an eyewitness recalled. "As soon as they gave them everything they had, they took off down the road, started trotting down, and we open the door and like, 'you guys alright? Y'all hit?"

The suspects may have gotten away in a red Nissan Cube.

Investigators are working to determine if the robberies are connected. If you have any information call Crime Stoppers at (804) 780-1000.