A D.C. firefighter is seriously injured and under investigation after he responded to a report of an injured toddler, the child's parents refused his help because they thought he was drunk or under the influence of drugs and multiple people beat him.

D.C. Fire and EMS is investigating allegations that the firefighter, who the department did not immediately name, was intoxicated, a statement issued Monday afternoon says.

"While still on the scene, allegations were made that the member who was assaulted was possibly intoxicated or under the influence of drugs," a statement from the fire department says.

A cellphone video obtained by News4 shows the firefighter being taunted on the street by several people in the moments before the assault.

"You're under the influence while doing your job?" a man can be heard saying.

Raw cellphone video obtained by News4 shows several people taunt a D.C. firefighter they accuse of being drunk. The video cuts off before the brutal attack.

The firefighter is downcast and simply flashes a peace sign.

"You need an ambulance yourself," someone else shouts.

The 40-second video ends before the assault begins. It's unclear where the firefighter's partner was at the time.

According to the department, the firefighter and EMT responded to a medical call on the 200 block of 37th Street SE about noon Sunday. A 3-year-old child was believed to be injured after falling.

The firefighter responded and offered treatment to the child but "the parents refused because they felt [the firefighter] was inebriated," a police report says.

As the firefighter and his partner headed back to their vehicle, several people beat the firefighter.

He suffered a broken jaw and is still in a hospital, the fire department said Monday. Initially, the department said his injuries were minor.

The toddler was taken to a hospital and treated, and is OK.

Once the firefighter is released from the hospital, he will be placed on administrative duty pending an internal affairs investigation. He has been on the job for nearly a decade.