Four members of a girl’s softball team for North Central Texas College in Gainesville were killed after a tractor-trailer crossed the center median and hit the team's van Friday night in Oklahoma, the Oklahoma Highway Patrol said.

Three of the victims died at the scene and a fourth died a short time later at Arbuckle Memorial Hospital in Sulphur, Oklahoma.

The four victims have been identified by NCTC Chief of Police James Fitch as 20-year-old Brooke Deckard of Blue Ridge, Texas; 20-year-old Jaiden Pelton of Telephone, Texas; 19-year-old Meagan Richardson of Wylie, Texas; and 18-year-old Katelynn Woodlee of Dodd City, Texas.

Two vigils are planned for Sunday. Brooke Deckard will be remembered at a 5:00 p.m. vigil at First Baptist Church in Blue Ridge.

Then Sunday at 8:00 p.m., North Central Texas College will hold a prayer vigil at its Gainesville campus in honor of all of the crash victims.

"This is the most traumatic event the campus has faced," NCTC President Dr. Brent Wallace told reporters early Saturday. "I want to offer sincere condolences to the girls' families."

The crash happened at about 9 p.m. Friday, on Interstate 35 just south of Turner Falls, Oklahoma, as the team was returning to Texas after a game with Southern Nazarene University in Bethany, Oklahoma.

Four Killed, 11 Injured in Bus Crash

Oklahoma Highway Patrol said the semi, being driven by 53-year-old Russel Staley of Saginaw, Texas, was traveling northbound on I-35 when the rig crossing over the median and collided with the softball team bus that was headed south. The bus was being driven by head coach Van Hedrick, 48, who has coached the team for 17 years.

The front end of the team bus was virtually untouched, but the sides of the vehicle were heavily damaged. Troopers and witnesses said the driver's side of the bus sustained the worst damage.

Oklahoma Highway Patrol Capt. Ronnie Hampton said that after the truck struck the bus it kept going and went off the side of the road.

"We knew we had a two-vehicle accident by what we saw at the scene ... But it took about an hour before we found the semi," he said.

The team’s bus rolled over in the crash and the semi then traveled into a wooded area on the side of the highway and was barely visible from the highway.

Hampton said more than a dozen others were hurt, including the driver of the tractor-trailer.

An OHP trooper told NBC 5 that three students were taken by ground ambulance to Paul’s Valley General Hospital in Paul’s Valley, Oklahoma and six others were taken to Mercy Hospital in Ardmore. Two other students were flown to OU Medical Center in Norman, which is a major trauma center. The coach, who was driving the NCTC bus, declined medical treatment at the scene. The driver of the semi-truck was taken to Paul’s Valley General as well.

Hampton said medical personal from four counties arrived on the accident scene. Fire, EMS and other personnel from several cities, counties and tribal agencies provided assistance.

“Any collision that results in death and someone could be charged with a crime is a homicide investigation,” Capt. Hampton said. “Our protocol for vehicle homicides is to have an accident reconstruction team come out and look at the technical aspects of the collision.”

Hampton said investigators will look at the semi driver’s hours of service and all the mechanical aspects of the semi-truck. A vehicle crimes investigator will re-create the crash and put together a comprehensive report for the district attorney in Ardmore. That report will include toxicology reports on both drivers and could take 10 weeks to finish.

Hampton said the driver of the semi provided OHP with a statement. When asked if the driver fell asleep, Hampton said there was no indication he fell asleep, but would not elaborate. He did say the mass casualty crash was one of the more difficult collisions he’s seen in the area.

“This would rank at the top of the list of severe crashes,” Hampton said. “You have to understand, a lot of times it’s not so much the damage that makes these things very dramatic, it’s the age and the quantity of the people that were killed.”

The National Transportation Safety Board will be investigating as well and is expected to arrive on Saturday.

"Right now, it's being investigated like a homicide," Hampton said, adding that both drivers will undergo standard toxicology tests. Hampton said details of the crash were still not known but "something happened to cause (the semi-tractor driver) to depart the roadway and impact the other vehicle."

He said the accident will remain under investigation for several weeks.

The NCTC softball team is one of four sports at the school. The following statement was posted to the team’s Facebook page early Saturday morning:

NCTC Softball would like to thank each and every one of you that has reached out to us tonight. We have a long road ahead of us but with power of God we will overcome! We lost 4 beautiful amazing girls tonight that truly blessed me day in and day out! Such sweet lives gone way too soon! Coach T and Coach Hedrick love you girls and you will be forever in our hearts.

"So my spirit grows faint within me; my heart within me is dismayed. I spread out my hands to you; my soul thirsts for you like a parched land. Answer me quickly, O LORD; my spirit fails. Do not hide your face from me or I will be like those who go down to the pit. Let the morning bring me word of your unfailing love, for I have put my trust in you. Show me the way I should go, for to you I lift up my soul." Psalm 143:4, 6-8

The team’s website lists 20 players on the 2015 softball roster. Twelve of the girls are freshman and eight are sophomores. Only 15 members of the team were on the bus and were accompanied by one coach, who was driving.

The campus in Gainesville is home to 2,485 students and all the athletes live in a dormitory on campus. It's a tight knit community, the president said. All other games have been canceled this weekend out of respect for those killed.

The college will hold a prayer vigil on Sunday at 9 p.m. ET, Wallace said.

The 2014 softball team made it to the NJCAA National Tournament in St. George, Utah, according to the 2014 softball schedule and the team’s Facebook page. The three sophomores killed were members of that team.

A post on the Facebook page for North Central Texas College asked for prayers:

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NBC 5's Christine Lee and Frank Heinz contributed to this report.