(CNN) — [Breaking news update, published at 3:13 p.m. ET]
The suspect in the shooting at a warehouse distribution center in rural Maryland has died of apparent self-inflicted wounds, Harford County Sheriff Jeffrey Gahler said.
She was a temporary employee at the facility, the sheriff said.
[Previous story, published at 3:09 p.m. ET]
A woman killed three people and wounded others at a drugstore distribution center Thursday in Harford County, Maryland, before shooting herself twice, officials said.
A source close to the investigation said the woman was a disgruntled employee. She shot herself in the head in an apparent suicide attempt, but was unsuccessful so she shot herself again, the source said.
A law enforcement official briefed on the incident, who provided the casualty toll for CNN, said the suspect was at some point a security guard at the Rite Aid support facility where the shooting occurred.
The suspect used a single handgun, Sheriff Jeffrey Gahler said at a news conference. The gunwoman is in custody and in critical condition at a local hospital, he said.
No law enforcement officers fired shots during their response, he said. Johns Hopkins Bayview Medical Center received four patients with “priority one gunshot wounds,” said spokeswoman Kristin Mears.
At a news conference, Ray Fang, the hospital’s trauma medical director, said two of the victims were stable and doing well, while two remain seriously injured. All the victims were out of surgery, he said.
It was not clear whether the shooter was among those treated, and Fang declined to provide additional information until he was sure all the victims’ families had been notified.
Rite Aid spokeswoman Susan Henderson said roughly 1,000 employees work at the distribution center, where products are received and processed for delivery.
“The shooting happened adjacent to the primary building,” she said. “What I understand is the location is secure.”
‘It’s right on the doorstep’
Colleen Hendrickson, who lives and works in the area, said she was waiting on the bus when someone told her there had been a shooting nearby.
“I, of course, thought it was far off or, that’s like down the road or something, right?” she told CNN affiliate WJZ. “No, it’s right outside. It’s right on the doorstep.”
She saw emergency vehicles, including ambulances, and helicopters, which were out of place for the “sleepy” part of the county, she said. The area is home to many warehouses and plants, some belonging to major brands, including makeup and bleach companies.
“It’s really just usually very calm, and this is the most chaotic I’ve ever seen it,” she told the station. “It’s very scary when it’s just right there on your doorstep because you can see a billion news reports about shooters, about emergency instances, and it still doesn’t make it real to you.”
People were being asked to avoid the area just outside the city of Perryman, roughly 30 miles northeast of Baltimore. Homes, churches and a cemetery are in the vicinity. Railroad tracks run alongside a business park.
Third mass shooting in a day
Deputies were dispatched at 9:09 a.m. ET, the sheriff’s office tweeted. They were on the scene in five minutes, Gahler said.
The Bureau of Alcohol, Tobacco, Firearms and Explosives sent agents from Baltimore. The FBI’s Baltimore office is also assisting.
“We are closely monitoring the horrific shooting,” Gov. Larry Hogan tweeted. “Our prayers are with all those impacted, including our first responders. The state stands ready to offer any support.”
This marks the third shooting with multiple victims in the country in the span of a day. A shooting at an office complex in Middleton, Wisconsin, left three people hurt Wednesday, and a gunman wounded four people at the Masontown Borough Municipal Center in Pennsylvania later in the day.
Police killed the shooters in both Wednesday incidents.
Harford County authorities responded to another fatal shooting in October, when a man killed three people and wounded two others at a remodeling business where he worked in Edgewood. The gunman later drove to Wilmington, Delaware, where he shot and wounded a sixth victim.