Summerside police arrested a suspect in an assault investigation in the Walmartparking lot Thursday afternoon. Police say they received a complaint about an alleged assault late Thursday morning. During the investigation police say they got additional information that a male at an Elm Street residence had a sawed-off shotgun. The suspect and two acquaintances were arrested outside WalmartThursday afternoon, then police executed a search warrant at the residence where they found and seized the weapon, according to a police news release. The suspect is in custody and is facing charges of assault, uttering threats and various firearms offences, the release said.