The precise timeline of the meltdown was still coming into focus, but Virginia transportation and law enforcement officials offered this timeline of events that led to extensive backups on Interstate 95.

• 3 a.m. Monday: The winter storm begins as rain.

• 5 to 6 a.m. Monday: The storm switches to snow.

• Morning Monday: State police troopers and wreckers start responding to stranded vehicles around the state.

• 8:20 a.m. Monday: State police receive their first calls about jackknifed tractor trailers on I-95 in the Fredericksburg area.

• 1 to 2 p.m. Monday: Snow stops in the area, and skies clear up. State officials are hopeful they can make progress moving vehicles but have little success.

• Afternoon Monday: A long queue forms as traffic inches along I-95.

• After 5 p.m.: VDOT says traffic was still flowing on I-95, though very slowly.

• 5:45 p.m. Monday: VDOT issues a news release saying northbound I-95 at Exit 140 is cleared and reopened. Another crash within the hour had again closed northbound lanes at Exit 133. VDOT says southbound traffic reopened at Exit 136. Officials note there was significant congestion.

• About 6 p.m. Monday: VDOT brings in more wreckers, tow trucks and personnel to the scene to move vehicles out of the way.

• About midnight early Tuesday: VDOT says there is a “complete blockage” of traffic, with the limited movement coming to a halt as icing worsens.

• Early hours of Tuesday: VDOT crews and contractors tow vehicles off I-95.

• About 4 a.m. Tuesday: VDOT decides to close I-95 to help workers get cars off the highway so they can use heavy equipment to cut through up to four inches of ice that had frozen to the roadway in some areas.

• 8 a.m. Tuesday: VDOT formally shuts down the already blocked I-95 to keep other motorists from entering and to help others make their way off the highway.

• 7 p.m. Tuesday: Lanes of I-95 reopened.