The person spoke on condition of anonymity because the investigation is continuing.
Police blocked road access to Jorden's home in an isolated area of private Lake View homes near the Lake Erie shore. SWAT team members in camouflage arrived in unmarked SUVs. A helicopter flew over the house then left.
Earlier, a SWAT team was called in to search a building on the hospital grounds. As of Wednesday afternoon, that search had ended but police were still collecting evidence at the hospital.
Police Commissioner Daniel Derenda said the morning shooting wasn't a random act. Police searched the building adjacent to the hospital's main building for the shooter more than four hours after the victim was gunned down inside.
The shooting prompted a four-hour lockdown of the medical center's 65-acre campus that was lifted at around noon for all buildings except the one being searched by police. Incoming patients were diverted to another hospital during the lockdown.
Police haven't released any information on the victim, other than her age. They have released no information on the suspected gunman.
Police said the woman was shot several times shortly after 8 a.m. inside a building that houses outpatient services and offices.
A police helicopter circled over the medical center's campus, which includes a 550-bed hospital. Officials said as many as 400 patients and about half of the hospital's 2,000 employees were on the grounds at the time of the shooting.
"Things are well under control by Buffalo police" and other law enforcement agencies involved in the investigation, Mayor Byron Brown said. He said state police, Erie County sheriff's deputies and suburban police departments were assisting.
"It's a very sad day for ECMC and our community," said Jody Lomeo, the medical center's chief executive officer. "Our thoughts and prayers are with the victim."
Nikita Patel, a 25-year-old University at Buffalo medical student from Los Angeles, said she arrived at the hospital about 9 a.m. for a class and was kept from entering. She texted fellow students inside the hospital to find out what was happening.
"They said they're locked in and can't get out of the hospital and I can't go in," Patel said.
Jorden received his certification from the American Board of Surgery in 2004. There are no legal actions against his license and he has no criminal background.
According to a 1996 profile in The Buffalo News, Jorden is certified in advanced-trauma life support and has received numerous awards recognizing his relationships with patients, his teaching skills and his involvement in the community.
The News reports that he is a Buffalo native who joined the National Guard in high school, went into the Army after graduation and served with the Army's Special Forces, first as a weapons expert, then as a medic. In those roles, he served in the Caribbean, Japan and Korea.