New London — Icy and slick conditions on the Gold Star Memorial Bridge caused multiple accidents Monday morning and contributed to a tractor-trailer becoming jackknifed in the afternoon, according to state police.

Gary Lessor, meteorologist with The Weather Center at Western Connecticut State University, said conditions were perfect to form ice on the bridge.

"The temperature was below freezing, but the pavement was warm enough to melt the snow," Lessor explained. "That combination results in ice."

Kevin Nursick, spokesman for the state Department of Transportation, said that he often sees more accidents with sporadic "dustings" than with blizzards.

"Statewide events are more manageable. Drivers see significant accumulation. It motivates them to slow down, to pay attention," he said.

"That doesn't happen with these storms," he continued. "These ones take the public by surprise."

He added, however, that drivers should know that bridges freeze first. "This is driver's ed 101," he said.

The DOT, he said, doesn't have a "magic wand" to make roads perfectly ideal during winter weather events.

"It is critical for people to understand that," Nursick said.

Police said they still are working to figure out exactly how many vehicles were involved in the morning accidents, which began around 8:30 a.m. and closed the bridge for about an hour.

Motorists stuck in traffic reported being at a standstill for at least 50 minutes.

Around 12:15 p.m., traffic again slowed to a crawl when a tractor-trailer jackknifed on the southbound side of the bridge and began spilling much of its fuel.

Approximately 100 gallons of fuel made its way into the Thames River through a drainage system, according to Dennis Schain, spokesman for the state Department of Energy and Environmental Protection.

"This was during an outgoing tide with winds out of the east. This kept the fuel in the center of the river and made it impossible for us to recover with booms or by vacuuming," he said in an email. "People downstream may notice/have noticed a sheen on the river."

The DEEP's Emergency Response unit prevented the remaining 175 gallons from leaking out, and an environmental contractor removed that fuel from the truck's saddle tanks, Schain said.

The Coast Guard was notified and was on the scene. 

Crews cleared the scene about 2:50 p.m., according to the DOT, but traffic remained congested for a short period of time afterward.

Nursick said crews had not pretreated the bridge before the snowstorm, but stressed that pretreatment is less about preventing accidents than making roads easier to clean.

He also noted that salt trucks were on scene quickly after snow began falling in the region.

"People think pretreatment is a 100 percent guarantee that you are not going to have slippery conditions," Nursick said. "Pretreatment is a tool that we have that can help improve driving conditions, but its primary function is to help us clean up faster — it helps reduce the bond of snow to the asphalt."

Pretreating all of about 12,000 miles of roadway the DOT is responsible for every time it snows isn't feasible, Nursick said.

"When we pretreat, it's less than 1 percent of roads ... and that takes all day," he explained.

Besides, he said, because the bridge and the roads surrounding it were wet from Sunday morning's storms, pretreatment wasn't an option.

An exact total of the number of accidents on the Gold Star Bridge was not available late Monday evening, but state police indicated that many had occurred.

Accidents also were reported elsewhere, including Ledyard, where police said there were 20 accidents, several with injuries, though none was serious. Lt. Ken Creutz attributed the high number of crashes to rapidly changing weather conditions and drivers not reducing their speed.

In Norwich, officials said 31 accidents occurred throughout the day.

As of 9:30 p.m. Monday, AAA said it had responded to more than 1,100 calls from drivers needing assistance across the state.

Most of the early calls were from Windham and Tolland counties, the agency reported, but calls became more concentrated in the greater Hartford region through the evening rush hour before finally tapering off about 7 p.m.

Lessor said it's "very common" to see snow in Connecticut in April and that much of the state will see more snow Monday night.

"The snow season doesn't just come to a conclusion," Lessor said. "It's something that, in New England, slowly goes away."

He said Groton, New London and other southeastern Connecticut shoreline municipalities may not see any snow Monday night because by 9 p.m., when temperatures will be right for snow, the precipitation already may have moved through the area.

But, he said, it's possible a cold front coming through the state on Friday could bring more snow to the region.

Day Staff Writer Kimberly Drelich contributed to this report.

l.boyle@theday.com