Update: A possible suspect was arrested on Friday in the shooting deaths of two people and wounding of two others at shopping centers in the suburbs of Washington, D.C.
Eulalio Sevilla Tordil, 62, an officer with the U.S. Department of Homeland Security, was suspected of killing his wife and shooting a bystander on Thursday in Beltsville, Maryland, in Prince George's County.
When a pair of shootings broke out in neighboring Montgomery County, investigators turned their attention to Tordil, who had threatened to commit "suicide by cop," police said.
Montgomery County Police announced his arrest on Twitter.
Authorities had temporarily locked down 14 schools near Friday's shooting sites and all of the county's recreational facilities as a precaution.
The shootings revived memories of the "Beltway sniper" attacks of 2002, when 10 people were killed and three seriously injured during a three-week spree in Washington, Virginia and Maryland.
Tordil is expected of fatally shooting his wife as she waited the parking lot of High Point High School in Beltsville to pick up her children. A bystander was wounded.