Interstate 105 was shut down in the Hawthorne area east of Los Angeles International Airport late Monday morning.
Los Angeles County fire Capt. Brian Jordan says mud is being pumped into the well and the flow of water has stopped, but he says danger remains.
The problem began Thursday, when there was an unexpected outflow from the well, which had been out of service for several years.
Thirty-seven families have been displaced from their homes. Golden State Water Co. says it is putting displaced persons up in hotels.
Golden State hired the well-known company Boots & Coots to cap the well.