SARDIS, Miss. — A rescue operation to transport around 50 dogs from Hattiesburg, Mississippi to Minnesota went awry Friday when the operation’s black van broke down on Interstate 55 near Sardis. Local animal advocates found about 12 dogs dead.

A truck driver traveling north to Pennsylvania pulled over when he saw dozens of kennels out along the side of the road.

Jessie Soto said he was horrified to realize at least 10 were dead.

Southern Pines Rescue group director Ginny Sims said the van left Hattiesburg around 1:30 Friday afternoon.

Sims said the rescue group has been operating since 1952 and has transported more than 11,000 animals in that time.

But this time, it didn’t go as planned.

They only made it to the Sardis area when Sims said the van broke down.

Witnesses said the van was pulled over on the side of the highway for two to four hours before local animal rescue groups could help.

“We pulled over to see what was going on. We knew it was animals. Sure enough, it was a lot of animals. Some of them dead, a lot of them in bad condition,” Soto said. “Those conditions were inhumane. It’s heartbreaking for people who love pets.”

Yvonne Tayler with the North Mississippi Animal Rescue said they came to offer aid.

“We needed to get the puppies and the dogs to a safe location where we could get them out of those crates cause those crates were nothing but heat traps and we brought them out here to my animal sanctuary,” Tayler said.

Tonight the remaining dogs are being cared for at the North Mississippi Animal Sanctuary.

They have water and food and a van is on the way to take them back to Hattiesburg.

Sims said they’d also dispatched their veterinarian to investigate the causes of death. She thought there was a mechanical malfunction in the van that caused the dogs to die. She considered carbon monoxide poisoning.

Sims said she didn’t think they could have just died from the heat.

WREG checked with the Panola County Sheriff’s Office. The Sheriff they said the Mississippi Highway Patrol responded to the broken down truck but didn`t see the need for any criminal investigation. However, the Sheriff said if he thinks it’s necessary he will pursue it.

This is an ongoing investigation. Check back for updates.