A Nassau officer fired least one shot at the suspect about 7:30 p.m., police said. A second suspect was taken into custody, police said.
Police said the officers were called to the shopping center by mall security who reported an incident involving the two suspects.
"We're trying to piece it all together," said Nassau Fourth Precinct Inspector Robert Psoinas.
Psoinas said there was a robbery at Walmart and officers confronted the robbers.
At least one suspect was in custody, one other fled and one was still being sought early Saturday, police said. An officer fired his weapon during the incident, police said, but no information was avilable as to whether any suspect was shot.
Late Friday, police had roped off about 10 parking spaces in the parking lot of the Walmart store adjacent to the mall. About a dozen officers, three police cars and a crime-scene van remained.