Investigators "have no idea" why a Maryland man shot and killed his parents at his home and shot two other people at a convenience store before setting fire to his house and killing himself, police said on Monday.
The gun used by Joshua Green, 27, during Sunday's massacre was registered with him and officially purchased in 2020, according to Colonel Andre Davis of Baltimore County.
"Why this happened, we have no information yet," Davis told a news conference. "Our detectives are relentlessly investigating the shooting, but it appears the shooter was working alone."
Police believe Green killed his parents - Douglas Green, 58, and Olivia Green, 62 - at their Baltimore County home before moving on to Royal Farms in Essex just before 7 p.m.
Green blocked another car park in the store, got out and shot and killed Alpha Smith, 62, while sitting in his car, according to Davis. Green then entered the store and shot and killed a customer, Silvesta Daye, 43, near the cash register before injuring a store employee. Davis said the employee, a 22-year-old man, was in a stable condition in hospital on Monday.
After the incident, police said Green returned to his nearby house and set fire to his house before shooting himself. Police found the house was full of flames and Green died in the parking lot with a gunshot wound.
Suicide investigators found the bodies of Green's parents in their garage when they went to them to inform them of their son's death, according to Davis.
Davis said Green "had no police-related crimes" prior to the incident.
Police chief Melissa Hyatt said "there are more questions than answers" about "a horrible and sickly event that changed the lives of so many people."
"At the moment, we know that four innocent people have lost their lives and one person was seriously injured," he said.
Hyatt said police spoke to Green's relative but did not elaborate.
“Once we have the facts and information, we will pass that on. We just want to make sure we put in the right information, ”said the chief.
Green's parents lived in the unincorporated part of Baltimore County called Baldwin. Daniel Brennaman, 73, a neighbor who lives in the two doors below the couple's home, said he noticed a police passenger saw a photographer outside the house while walking with his dog on Sunday evening.
"There was a storm here, and I thought it was a car accident in the corner," he said. "I didn't hear anything."
Brennaman said he had greeted small conversations with the couple but did not know them personally.
"I tease him from time to time. He always works in his yard," he said.
Royal Farms spokeswoman Trena Brown said on Sunday the company had no immediate comment on the shooting of its store.