Denise Hollinshed is a reporter for the St. Louis Post-Dispatch
University City Police said Jiangying Deng, 77, was attempting to cross the 8300 block of Delmar
Both were taken to hospital with injuries.
Police said the driver of the vehicle that struck the woman is cooperating with detectives.
Suspect, victim knew each other, but motive not clear.
Authorities identified the victims as Michael Ladd, 79, a local contractor, and his wife, Lois Ladd, 68, an Edwardsville chiropractor.
The Illinois State Police identified the man Sunday as Billy L. Walker Jr., 53, of Hillsboro.
The person was alone inside the business, at Pernod and Brannon avenues, police said.
The school district released few details but said that it is cooperating with authorities.
Killer fired from another vehicle, authorities say.