Five fatalities of horses being hit by cars since April along Bush Highway, three of them within the past week, have prompted new safety measures to warn drivers.

Several message boards were placed along the highway, cautioning drivers to “slow down” and to “watch for horses,” according to Tracy Ruth, communications-division manager for the Maricopa County Department of Transportation.

Other commitments include working with the Maricopa County Sheriff’s Office to enforce speed limits and painting “watch for horses” signs on the asphalt.

Simone Netherlands, president of Salt River Wild Horse Management Group, a non-profit organization that protects the wild horses, said the Transportation Department committed to short-term and long-term plans to improve safety along Bush Highway.

“We really want to commend them for their fast action,” she said.

Netherlands said the increase in fatalities may have resulted from the recent addition of guardrails along portions of Bush Highway.

“The horses were getting confused by the guardrails, they kept walking into them,” she said, and were stuck within the confines of the road at times.

Since April, five horses have been killed. Two of the horses had unborn foals. No people have been seriously hurt in the collisions, according to the non-profit group.

Ruth said the county’s Transportation Department has worked with the non-profit group for nearly five years, but immediate action was necessary because “it had become a significant issue.”

Ruth said some of the long-term safety measures may be completed within the next year. These include installing speed “flashback” signs to remind drivers when they exceed speed limits and placing horse-crossing signs.

The county also will work on developing long-term solutions, including radar-triggered flashing lights that are activated when horses are on the road.

Bush Highway cuts across the habitat for the Salt River horses, a herd that has long been the subject of advocacy and debate.

In August 2015, the U.S. Forest Service announced it would round up and remove the herd of about 100 horses that roam near the Salt River Recreation Area. The Forest Service said the horses were causing safety issues, including traffic collisions on the Bush and Beeline highways.

An outcry from animal lovers and politicians halted the planned roundups, and an agreement to protect the free-roaming horses was announced in December 2017.

Under the agreement, the horses are no longer considered stray wildlife and the law makes it illegal to slaughter, harass, shoot, injure or kill the horses.

Republic reporter Jessica Boehm contributed to this article.