SOUTH GATE (CBSLA) — Four men were killed Wednesday after their BMW lost control on the northbound 710 Freeway and crashed into a freeway sign pole at high speed.

The first reports of the crash started at about 3:15 a.m. Callers told 911 two cars were racing on the freeway when one passed the Firestone Boulevard exit, lost control, went through a guardrail and slammed into a freeway sign pole.

A man who identified himself only as Alex says he heard the horrific boom of the impact and jumped the block wall fence behind his home to try to help.

“Like, I never seen anybody trapped in a car like that. The image is stuck in my head, you know?” he said.

The force of the impact catapulted the engine from the BMW, and sent several car parts over the wall and into Alex’s pool.

The BMW was left on its side, wrapped around the freeway sign pole. Four men were inside the car, and all were killed on impact. Two of the men were 22 years old, and all four identities have been withheld pending notification of their families.

Family members of at least one of the men had already pulled up to the scene of the crash, and tried to free the men, but metal was caved in all around them. The CHP said one of those family members put his fist through a car window in his grief.

CHP says there were significant skid marks leading up to where the BMW crashed, but there’s no sign of a second car. Investigators say it’s not clear if a second was indeed involved, or if the BMW was simply speeding.

Three of four lanes of the freeway were shut down for several hours after the crash. By noon, only the right lane remained closed so the guardrail could be repaired.

CHP investigators say they plan to look into how the family was able to arrive so quickly — whether they were driving to a destination with the BMW, and if they can shed more light on the moments leading up to the crash.