A person hurled concrete debris at a Mercer Island Fire Department ambulance while its crew was transporting a patient along Interstate 90 to Seattle for medical treatment in the early morning of July 20.

No one was injured during the incident, which occurred at approximately 3 a.m. near the Rainier Avenue exit when the subject threw the debris while standing on the far right side of the interstate, according to the city. The vehicle received a scuff on its suspension from the debris.

The ambulance driver swerved away from the debris, and the crew immediately alerted the Washington State Patrol (WSP) before continuing its trip to the Seattle hospital.

WSP has arrested a suspect in the incident. Earlier, a suspect evaded state troopers.

“Fortunately, Washington State Patrol were actively patrolling the area, they responded immediately,” said City Manager Jessi Bon at the city council meeting on July 20. “We know they’ve been working really hard on this and we’ll provide more information as it becomes available.”

Since early July, several similar incidents have occurred on I-90 and Seattle Police and state troopers have made two arrests in connection to these crimes. WSP has assigned six state troopers to patrol the area, and Mercer Island Police Department Chief Ed Holmes has been in direct contact with the WSP captain assigned to the cases.

“The City of Mercer Island takes these crimes very seriously and strongly supports the apprehension and prosecution of those responsible. Efforts to catch those responsible, and to stop these incidents from continuing, are ongoing,” according to the city.

Bon said people have been concerned about the debris-throwing situation.

Of the many comments from posters on the Mercer Island fire and police Facebook pages, one read: “We need fencing and/or another barrier on overpasses! This is not an isolated occurrence and further injuries need to be prevented.”

Added city staff: “Drivers are urged to keep a watchful eye on the road and surrounding terrain when passing through the area. If you see anything suspicious, call 911 immediately.”

Mercer Island firefighters were on the scene of a similar incident on the evening of July 18, when a piece of concrete crashed through a driver’s windshield while she was traveling westbound through the I-90 Mt. Baker Tunnel. Firefighters transported the driver — who sustained head and neck injuries — to an area hospital.

That same day, local firefighters assisted occupants in two of three additional vehicles that were struck by concrete and debris while traveling west on I-90 near the exit to Rainier Ave South. They removed the shattered glass from the exposed skin and clothing of three uninjured occupants.

On Mercer Island Fire’s Facebook page, it reads that, “Mercer Island receives mutual aid from Seattle and King County emergency services. Mutual aid agreements allow first responders across our region to address the closest incidents as quickly as possible.”