Colorado State Patrol

The Colorado State Patrol says four people were killed in a crash on I-25 south of Pueblo involving at least 30 vehicles on Tuesday morning. Investigators said there were heavy winds in the area at the time of the crash, blowing dirt and causing "brownout" conditions with low to no visibility for motorists.

The crash happened just after 10 a.m. in the northbound lanes of I-25 at mile marker 92, just south of Pueblo Boulevard. Pueblo is about 40 miles south of Colorado Springs.

According to investigators, there is a preliminary estimate of at least 30 vehicles involved, including six semis and passenger vehicles. Some of the vehicles involved were pulling horse trailers, and some had animals inside.

The scene of the deadly 30-vehicle crash on I-25 near Pueblo./ CBS

State troopers said there were four confirmed fatalities and multiple reports of injuries, with 29 people rushed to area hospitals. Investigators said the four people killed were in separate vehicles. For those injured, the injuries range in severity from minor to serious, but the exact conditions of those treated were not immediately known.

Near the deadly crash scene on I-25 south of Pueblo, blowing dirt contributed to low visibility. /KKTV

"We had the advisories the wind was going to pick up this morning, there were no closures and this was one of those storms that came through and the wind picked up very quickly and that location down there, unfortuantely, due to the lack of moisture and stuff that we`ve had in the area, the dirt and everything just transversed all the way across I-25 and created just a... call it a dirt or a brownout," said Brian Lyons with the Colorado State Patrol.

Northbound I-25 was closed at mile marker 93 and southbound lanes of I-25 were closed at mile marker 94. Investigators have advised drivers to avoid the area due to the closure and low visibility until conditions improve.

A deadly crash in the southbound lanes of I-25 south of Pueblo involved at least 30 vehicles. CDOT

Investigators said the northbound lanes would remain closed for some time during the investigation and crash cleanup. They said a secondary crash happened in the southbound lanes in the same area and under similar conditions. Troopers and other agencies worked to clear that scene and reopened the southbound lanes to traffic just after 2 p.m.

It was unclear when the northbound lanes of I-25 would reopen to traffic, but state troopers said to expect a lengthy closure.