Flames shot out of U.S. 50 in the casino core early Easter morning, after a power component caught fire and exploded.
The blast left a crater in the middle of the highway and cracked a natural gas pipeline, causing a leak at 5 a.m. Sunday.
The cause of the explosion is still under investigation, NV Energy spokeswoman Kristen Saibini said Tuesday.
"NV Energy experienced an electrical event in an underground vault," she said.
Utility workers spent much of the day just getting to the point where they could get close enough to work on the electricity.
Meanwhile, Douglas County and Nevada authorities called out the reserves to shut the highway down so utility workers to conduct repairs.
Members of the Sheriff's Search & Rescue, Citizens Patrol and reserves aided in keeping traffic and pedestrians clear of the corridor.
Tahoe-Douglas firefighters, NV Energy and Southwest Gas utility workers also responded.
No one was reported injured in the blast, but about 400 NV Energy customers were without power until about 8:15 a.m. Sunday.
While power was out, most of the casinos and other businesses operated on generators. The odor prompted firefighters to investigate at least one report of fumes, but it was determined to be unfounded.
Two lanes of the highway reopened around midnight, with power fully restored to the casino corridor by 5:14 a.m. Monday, Saibini said.
Nevada Department of Transportation spokeswoman Meg Ragonese said both eastbound lanes of the highway were open on Tuesday, but westbound motorists were being detoured onto Lake Parkway.
She said there is no timeframe for completion of repairs. Motorists should anticipate closed lanes through the casino corridor over the next few weeks.
"NV Energy and other utility partners will continue repairing damaged utility infrastructure, following which NV Energy will repair the damaged roadway," she said. "We at NDOT will partner with NV Energy during roadway repairs by providing inspections to ensure that repairs meet standards and specifications for highway safety."