Authorities said Dayle Veronica Downs-Totonchi, 47, died at a Phoenix hospital Friday night. Two other Arizonans and a Louisiana man were killed at the scene of Thursday's accident.
One person - Phoenix Fire Department Capt. Ernie Lizarraga, 52 - remained hospitalized in critical condition Friday with three others in serious condition, police said. Another man was treated and released.
The two Phoenix-area men killed when the truck hit the eight motorcycles from behind were identified earlier Friday as Clyde R. Nachand, 67, and Daniel L. Butler, 35. Police said the Louisiana resident was Stephen Punch, 52, of Lockport.
There was no sign that truck driver Michael Jakscht, 46, was impaired, and no charges have been filed, Phoenix police spokesman Officer Luis Samudio said.
One witness who said she talked to the truck driver told The Arizona Republic that he appeared to be in shock after the wreck.
"He told me he wasn't paying attention, just shuffling with his paperwork," said Tania Krukoff, an employee of a nearby Walgreens who rushed to the scene.
Samudio said detectives have not been able to confirm the driver made that statement.
The Arizona Republic cited court records as showing that Jakscht was cited in Scottsdale on March 15 with driving at an unreasonable speed. According to the records, he was traveling 45 mph in a 45 mph zone but failed to control his speed to avoid an accident. The Republic said he was also cited in recent years for excess vehicle weight and equipment violations.
The eight motorcycles, carrying nine people, had pulled up behind a pickup and a small SUV at the light Thursday afternoon when the truck driver rammed them from behind, police said. The truck ran over the motorcyclists and continued into the SUV.
Some of the motorcycles burst into flames under the dump truck, while others ended up scattered behind the truck. The crash site was a horrifying collection of mangled chrome Harley-Davidson and other heavyweight bikes and scattered personal belongings, including pairs of riders' boots laying in the roadway.
Jarrod Cook, a worker at the nearby Ketzal Mexican Grill, said he saw several motorcycles wedged underneath the garbage truck, which caught fire.
"The first thing we saw was a big puff of smoke when the truck lit on fire," he said.
Cook said he walked over and witnessed a chaotic scene with some of the injured lying on the ground.
Police investigators will complete their probe, then determine if charges or citations are warranted, Samudio said.
By Associated Press Writer Bob Christie