An ice scraper is used to chip the ice off a car door window in Alexandria Va., Dec. 17, 2016. (John McDonnell / The Washington Post)

The roads had been pre-treated and warnings issued to the driving public to stay off the roads, but the Washington region’s first winter event still caught many unprepared.

Many travelers ignored the warnings and ventured out in Saturday’s freezing rain, triggering hundreds of crashes. Authorities reported four fatalities.

It turned out to be one of the busiest days of the year for first responders. Transportation officials said pre-treatment materials washed away and road conditions quickly deteriorated even as crews stayed on the roads.

Saturday’s events offered a taste of what winter could bring, and officials said they hope the takeaway for residents is to take warnings seriously and closely monitor conditions.

“As the winter storm season begins, we urge all Marylanders to use caution when traveling, closely monitor weather and road conditions, heed all warnings from state and local authorities, and have a safety plan in place for emergencies,” Gov. Larry Hogan (R) said in a statement.

The storm early Saturday led to at least two deadly chain-reaction crashes: one involving 23 vehicles on the Capital Beltway in Fairfax County and a 55-car piled up in Baltimore. As of Sunday afternoon police had not identified the four victims.

In Maryland, state police said they responded to more than 370 crashes across the state. The most serious incident, involving the 55 cars on Interstate 95, began after a tanker went off the highway and burst into flames early Saturday.

Two people died in that incident, including the tanker driver and another driver who was hit by debris. Officials said at least 12 others were transported to local hospitals.

Maryland officials say from midnight Friday until midnight Saturday troopers provided assistance to 95 disabled vehicles and stranded motorists in the state. The state police responded to 377 traffic crashes, including 60 in Prince George’s County, 33 in Frederick and 34 in Baltimore County.

Of those, 56 involved injuries and 131 left damage to one or more vehicles. In 190 of the cases, the vehicles could be driven from the scene.

In Virginia, a 23-vehicle pile up occurred on the Beltway in Fairfax just after 5 a.m. A short time later, about a mile away, a man’s body was found on the highway shoulder. Authorities said Saturday that it appeared the man was involved in the wreck and had walked away, though it was unclear how he died.

A fourth person was struck and killed by a tractor-trailer near the Bayview area of Baltimore about 5 a.m.

Authorities closed roads for hours, and public transportation was halted during the morning because of icy roads.

Virginia transportation officials had asked drivers to stay home between 3 a.m. Friday and 9 a.m. Saturday, when low temperatures could cause icy road conditions.

“If travel is necessary, allow extra time to reach destinations, lower speed and keep a safe distance from other vehicles,” the Virginia Department of Transportation advised.

By 6 a.m., the National Weather Service’s Twitter account sent a message to people to “STAY OFF THE ROADS this morning!” By 10 a.m., VDOT sent another reminder: “Driveway frozen? Perfect indicator to avoid heading out just yet. It’s slick everywhere — take a couple hours if you can.” And D.C. police followed with the warning that it was “slippery and wet out! Avoid dangerous conditions.”

It appears many people didn’t get the message.

Higher temperatures followed Saturday’s ice. But forecasters Sunday were calling for the return of chilly conditions and the possibility of thunderstorms and windy conditions by Sunday afternoon.

On Sunday, at least one weather-related incident was reported: Several sailboats overturned in the Potomac in the early afternoon, and three people had to be rescued from the waters. Officials said the boats probably overturned because of high winds.

“Cold front coming through DC area is for real,” The Washington Post’s Capital Weather Gang tweeted, warning about another arctic front moving through the region. “Expect very fast 10-20 degree drop in temps and gusty winds.”