A man and a woman were seriously injured Monday in separate accidents that closed a portion of Interstate 43 for about two hours on Green Bay’s far east side.

Northbound lanes of I-43 and a southbound lane from East Mason Street to North Webster Avenue were closed for nearly two hours. Accident reconstruction crews are investigating the incidents, Green Bay police Capt. Bill Galvin said.

A 31-year-old Green Bay man on a motorcycle was taken to a local hospital with severe injuries about 11:30 a.m. after he crashed into a guardrail on I-43 near University Avenue, Galvin said.

The man, who was not wearing a helmet, was traveling from Wisconsin 54/57 to I-43 north and failed to negotiate the curve on the ramp. He drove onto the outside shoulder of the ramp, over the grassy area between the ramp and the highway lanes and eventually struck a guardrail at the highway median.

The crash, which is still under investigation, created a backup of traffic on I-43.

Just a few minutes later, a 68-year-old woman was seriously injured after her vehicle struck the back of an SUV that was stopped in the outer northbound lane due to the previous crash. That accident happened near the Humboldt Road overpass, Galvin said.

The impact pushed the SUV into the median where it rolled onto its side. The driver of the SUV, a 47-year-old man, and a 47-year-old passenger were taken to a local hospital with minor injuries.

The woman driving the vehicle that hit the SUV sustained serious injuries. She was taken to a local hospital along with her 19-year-old passenger, who had minor injuries.