"Earlier today Downey police personnel developed information that led to the detention of an adult subject matching the description of the suspect involved in the fatal shootings," said Downey Police Department Lt. Dean Milligan.
A suspect opened fire in the 8700 block of Cleta Street at United States Fire Protection, a family owned and operated business, just after 11 a.m. Wednesday, shooting three people.
"Never heard anything. I swear to God, that guy must have had a silencer," said Dean Wright, who owns the business next door.
The gunman then got into a black 2010 Chevrolet Camaro and traveled two blocks to the family's home on Cleta Street, where two more people were shot.
Police said three men and one woman were detained Thursday, but no arrests were made. In an 8 p.m. news conference, police said a 2010 Chevrolet Camaro that was being sought had been found. Police said one male remained detained and the other three were released.
Three of the five shooting victims died and the two survivors, including a 13-year-old boy, remained in critical condition. According to police, the victims are all members of the same family. A coroner identified the victims as a Hispanic man in his 20s and two Hispanic women in their 30s.
Two of Wednesday's shooting victims were identified late Thursday. Those identified were Cudahy resident Irene Cardenas, 35, and Downey resident Josimar Rojas, 26.
A neighbor, who wanted to stay anonymous, posted on Twitter that the woman who was killed at the house was Susana Perez. That neighbor said the 13-year-old boy who was wounded is Perez's son.
The Camaro belonged to one of the victims, police said. The Camaro has a California license plate 6LEA010, and its front license plate is missing. It was located Thursday.
A motive remains unknown, but detectives believe the family was targeted. There were no signs of forced entry at the business or home, police said, and some kind of conversation took place between the gunman and victims.
There are few details about the gunman. According to police, the suspect they are looking for is an African-American man standing about 6 feet tall and weighing about 230 pounds.
Anyone with information related to the case is urged to call the Downey Police Department at (562) 904-2340.