A fiery and deadly seven-vehicle crash on Interstate 94 in western Wisconsin was triggered when a trucker traveling "at highway speed" slammed into a string of vehicles that had slowed for a construction zone ahead, officials said Tuesday.

The pileup that occurred shortly before 5:40 p.m. Monday on westbound Interstate 94 south of Wilson and 28 miles east of the Minnesota border claimed two lives and injured six other people, according to the Wisconsin State Patrol.

Killed were the driver of the semi-trailer truck and the motorist in a pickup truck that was the first vehicle struck, the patrol said Tuesday. The injured were treated at the scene and did not require hospitalization, added the patrol, which has yet to release their identities.

The dead were identified Tuesday night as semi driver Zdzislaw Obodzinski, 76, of Palatine, Ill., and the pickup driver, James Michael Shearer, 45, of Hammond, Wis.

A 36-year-old man from Minneapolis driving an SUV sustained non-life-threatening injuries, as did his three passengers, a 38-year-old woman, a 6-year-old girl and a 16-year-old boy.

A 37-year-old man from Hagersville, Ontario, who was driving in another pickup truck also sustained non-life-threatening injuries, the State Patrol said in the Tuesday night update.

Five others were in the crash but did not suffer injuries, according to the State Patrol.

A fair amount of the burning wreckage ended up below the interstate overpass for Hwy. 128. State transportation officials later closed the overpass for a safety inspection and reopened it to traffic midday Tuesday.

Troopers responding to the scene told emergency dispatch that it was not immediately clear what the semis were hauling, but one of them said, "I do have lots of little explosions going on inside."

The patrol's first update Tuesday noted that westbound traffic had been backing up because of a construction zone 2 ½ miles from the crash scene.

The semi driver was "traveling at highway speed, failed to identify the slowed traffic ahead" and struck the pickup and a second semi, an update read. Four other vehicles were caught up in the chain-reaction crash, the patrol added.

State Department of Transportation video shows the semi heading toward a line of vehicles that were moving much more slowly before the big rig plowed into the back of the pickup truck and the other semi.

A fiery explosion burst from the second semi and the pickup. An SUV in the left lane was then hit by the crushed pickup.

The vehicles rolled out of view of the camera as a trail of flames was left on the pavement.

About 4 minutes later, the traffic camera revealed the heavy black smoke enveloping the overpass as both semis and other vehicles continued to burn.

Staff writer Louis Krauss contributed to this report.