At about 8:50 p.m., surveillance cameras captured a man walking towards the victims in a grocery store parking lot in the 700 block of Greens Road.
The suspect is seen pulling out a pocketknife and placing it on the back of one of the victims, forcing both to the ground and demanding their property.
RELATED: Video shows 2 teenage suspects rob southeast Houston store at gunpoint, HPD says
The suspect then runs away from the area with both victims' wallets and cellphones.
According to officials, the suspect is described as a Black man in his 40s, wearing a gray mechanic suit with a black hoodie and a mask only showing his eyes and forehead.
Crime Stoppers of Houston is offering up to $5,000 for any information that leads to the suspect's arrest and or charging of the suspect. Tips can be submitted online, or by calling 713-222-TIPS (8477).