OMAHA, Neb. -- Between Monday and Tuesday, authorities responded to four robberies in Omaha. 

Monday morning, the Omaha Police Department said they are investigating an attempted robbery that happened at One Main Financial, 12103 West Center Road.

Officers responded to the business at 10:03 a.m. and spoke with the store's employees.

Authorities said that investigators determined that a black female wearing a mask entered the business, showed a handgun and demanded money.

Officials said the business was unable to provide money to the suspect. The suspect left the area heading eastbound.

Several hours later, OPD said they are investigating a robbery that happened late Monday at the Mega Saver at 6000 Grover Street.

OPD Officers responded to the call at 10:58 p.m. and they spoke with employees who said the suspect entered the business, showed a firearm and demanded money.

Authorities said the suspect took cash and left the store on foot heading west.

In a press release, the suspect was described as a black male in his 20s, 6', wearing a black hat, gray jacket and dark pants.

Tuesday morning, Omaha Police said they are investigating a robbery that occurred at the Speedee Mart at 120th and Pacific Street.

OPD Officers said they responded to the store at 1:34 a.m., and they spoke with an employee who said a black male wearing dark clothing robbed the store at gunpoint.

Authorities said the suspect left on foot heading westbound.

About a half-hour later, Omaha Police said are investigating a robbery that happened at the Speedee Mart at 132nd and Grover Street early Tuesday.

OPD Officers said they responded to the store at 2:06 a.m. and spoke with an employee who said a black male wearing dark clothing had robbed the store.

Authorities said the suspect approached the counter, showed a handgun and demanded money.

The suspect took cash and left the store heading northbound on foot.

These are all ongoing investigations.