The accident scene covers about 1.5 miles.
Several people are trapped after a pile-up on the highway in Fort Worth, Texas, according to the Fort Worth Fire Department.
At least 50 cars are involved, including some that are stuck under others, a police source told ABC News.
The number of people arrested was not immediately clear.
Fort Worth police blamed the weather for the I-35 accident – freezing rain caused slippery roads in the Fort Worth area.
The accident scene covers about 1.5 miles, reported ABC affiliate Dallas WFAA.
“Expect long delays,” warned the police in a tweet. “I-35 is backed up in both directions from I30 to 820.”
“If you are involved in a minor accident with no injuries, please exchange information and stay safe. You can then notify your insurance when you arrive at your destination,” tweeted the police.
This is a developing story. Please check again for updates.