Several lanes on the eastbound 60 Freeway in Diamond Bar are closed after two big rigs crashed causing one of them to turnover. 

The California Highway Patrol issued a Sig Alert on the eastbound 60 Freeway west of the northbound 57 Freeway. Three lanes are closed, and it is unknown when they will reopen.

One person was pronounced dead at the scene. It is unclear how the incident took place.

Authorities are asking drivers to travel with caution and use alternate routes while crews work to clear the roadway.