Police say a gunman who shot and killed three people and injured four in northeast Arkansas was an acquaintance or friend, but a motive is unknown.

Jonesboro Police Sgt. Doug Formon says the shooter was 40-year-old Porfirio Hernandez, who recently had been released from a mental health treatment facility.

A 38-year-old man and a 12-year-old girl were killed Saturday afternoon at a home in Jonesboro, and four others were injured. About 20 minutes later, police received a call about a shooting at a business, where a 31-year-old man was found dead.

Hernandez was later found dead of an apparent self-inflicted gunshot wound.

Three people are in critical condition in Memphis, Tennessee, hospitals: a 43-year-old man, a 36-year-old woman and an 8-year-old boy. A 10-year-old boy is in stable condition.