Shortly after dawn Wednesday, a 22-year-old driver plowed a Honda CRV into a large group of recruits with the Los Angeles County Sheriff’s Department who were on a training run in South Whittier. Dozens were injured, at least five of them critically, authorities said.

The California Highway Patrol is leading an investigation into the crash.

Here is what we know so far.

When and where did the crash occur?

Dispatchers received a call just before 6:30 a.m. about a crash involving pedestrians in the 10600 block of Mills Avenue, the Sheriff’s Department said.

The crash occurred near a training center for sheriff’s recruits, called STARS Center Academy in South Whittier.

Recruits were running near Mills Avenue and Trumball Street in four columns when a vehicle approached the group at 30 to 40 mph, Sheriff Alex Villanueva said. The vehicle was traveling in the wrong direction, Los Angeles County Fire Capt. Sheila Kelliher said.

What happened after?

Video shot by a man who lives across the street from the crash showed recruits desperately trying to treat the most badly injured, who were immobilized and bloody on the ground as smoke still spewed from the driver’s SUV.

Voices shouting for more assistance and giving instructions can be heard as groups of the less injured gathered around those who were most seriously hurt, trying to render aid. Some of the recruits were emergency medical technicians, and at least one in the group was a trained nurse.

Several deputy recruits were also able to knock on the door of a fire station 500 feet from the crash site and ask for help, said Anthony Marrone, interim chief of the Los Angeles County Fire Department.

What prompted the crash?

The cause of the crash, including any motive behind it, is under investigation.

Authorities said the driver was traveling south on Mills Road before he veered into the northbound lanes, where a group of about 75 recruits was jogging in a large formation. The runners were being escorted by two black-and-white patrol cars. Eight road guards wearing reflective vests also were present.

The recruits at the head of the pack saw the SUV careening toward them and dived out of the way, authorities said. Those toward the back of the formation did not see the oncoming vehicle before the driver plowed through them and then slammed into a light pole, knocking it to the ground.

The pole stopped the car’s momentum and prevented the vehicle from striking other recruits, authorities said.

The driver, who has not been identified, was detained at the scene by cadets.

Authorities detected no smell of alcohol on him, and he “blew a 0.0" during a Breathalyzer test administered at the scene, Villanueva said.

Who are the recruits?

The 75 sheriff’s deputy recruits are members of Class 464 with the STARS Center Academy, a training center in South Whittier. Recruits with police departments from Bell, Pasadena, El Segundo, Glendale and UCLA also were in the group that was running, Villanueva said.

Approximately 10 of the recruits are female, authorities said.

This was the group’s eighth week of training, Villanueva said. The program last 22 weeks.

What are the extent of the injuries?

Twenty-five recruits were injured in the crash, authorities said. At least five were taken to hospitals in critical condition.

Villanueva called the injuries “life-altering” and said they included head trauma, broken bones and “some loss of limb.” One of the five critical patients was on a ventilator.

At least two patients were airlifted from the scene, authorities said, and taken to hospitals, including L.A. County-USC Medical Center in Los Angeles, PIH Health Whittier Hospital, UCI Medical Center in Orange and St. Francis Medical Center in Lynnwood.

The driver also suffered minor injuries, including scrapes, and was transported to a hospital.

Who is the driver?

The driver is a 22-year-old man from Diamond Bar. Authorities did not release any additional information about him Wednesday.

Investigators are looking into his background and have learned his uncle is in law enforcement. They say his initial behavior could suggest he was under the influence. They also said they found marijuana in his vehicle.

Have charges been filed?

No charges have been announced in the incident.

At least five recruits are in critical condition after a car plowed into L.A. County sheriff’s cadets jogging along the street on Wednesday early morning near Whittier.

(Irfan Khan / Los Angeles Times)