Update, 4:05 p.m.:

The two closed northbound lanes on Connecticut Avenue should remain closed through the afternoon and evening commute, with just one northbound lane open to traffic, said Kira Calm Lewis, a spokeswoman for the Washington Suburban Sanitary Commission.

As Drivers who normally use Connecticut Avenue should use alternate routes. If you have to head that way, expect to encounter severe delays as you approach the area between East-West Highway and Jones Bridge Road.

— Mark Berman

Update, 3:45 p.m.: 

One lane has reopened on northbound Connecticut Avenue following the earlier water main break.

Update: 12:40 p.m.:

The northbound lanes of Connecticut Avenue remain closed between East-West Highway and Jones Bridge Road.

A thick layer of mud coated Connecticut, while a large chunk of Chevy Chase Lake Drive east of the intersection had been blown away by water, leaving behind an enormous crater about 20 feet deep.

WSSC spokesman Jerry Irvine said crews hoped to have at least one or two lanes of northbound Connecticut reopened for the afternoon rush.

— Katherine Shaver

Updated 7:09 a.m.

All southbound lanes of Connecticut Avenue south of the Capital Beltway were reopened just after 7 a.m. Tuesday, following a huge water main break that led to a downed tree and power lines in Chevy Chase, Md. Residual traffic delays are expected.

Updated 7 a.m.

A massive water main break in Montgomery County is snarling traffic on Connecticut Avenue near the Capital Beltway Tuesday morning.

Connecticut Avenue is closed to commuters in both directions between Jones Bridge Road and between Manor Road, just south of the Capital Beltway in Chevy Chase, Md., Montgomery County police said.

[Read the latest updates here.]

The closure began around 8 p.m. Monday, when a 54-inch water main broke at the intersection of Connecticut Avenue and Chevy Chase Lake Drive. Crews worked overnight to secure the natural gas and electric lines that run alongside the water main and to control the huge plume of water erupting from the main, which at times gushed as high as 30 feet high.

Flooding caused soil to soften and a tree to fall, taking down power lines with it.

No injuries were reported, but the fallen tree derailed efforts to open the roadway by the start of morning rush hour. Police said the inbound lanes of Connecticut Avenue, a major artery into downtown Washington from Montgomery County,cannot be opened until the downed power lines are cleared.

Because of the enormous loss of water — an estimated 60 million gallons — the Washington Suburban Sanitary Commission has issued mandatory water restrictions for all customers in Montgomery and Prince George’s County. Pepco crews are working to restore power to about 1,100 households.