BROOMFIELD, Colo. -- It was a somber start to homecoming week Monday at a suburban Denver high school after a bus carrying football players and coaches crashed at the airport, killing the driver and injuring 18 passengers, some critically.The bus driver was speeding as she veered off a roadway and slammed into a concrete pillar Sunday afternoon at Denver International Airport after picking up members of the Legacy High School football squad.The students were returning from a football game in California, and the vehicle was circling back to the airport for an unknown reason when it crashed.Detectives spent hours interviewing witnesses, including those aboard the bus, but no one could explain why the driver headed back toward the terminal before driving directly into the pillar, Denver police Sgt. Mike Farr said.Theres a big mystery there, he said.The driver was traveling 30 to 40 mph (48 to 64 kmh), too fast for that stretch of roadway, Farr said. Tire tracks show she made no attempt to avoid the pillar.Police were investigating the possibility she suffered a medical condition. They were also inspecting the bus for mechanical problems.Theres no evidence the driver crashed intentionally, Farr said, but certainly its one of the things we have to be open to.The bus carried 28 students and four adults, airport spokeswoman Heath Montgomery said.Fifteen students were taken to hospitals with minor injuries as a precaution, school officials said. Three coaches remained hospitalized Monday with serious injuries.Authorities identified the driver as 43-year-old Kari Chopper.Two victims at Denver Health Medical Center were in critical condition, two in serious condition and one in fair condition.The crash stunned students at the school in Broomfield, north of Denver. A crisis team was there to help.Junior Kevin Segura was relieved to learn that his friend, a football player, was OK.He was released from the hospital last night. Hes just really traumatized right now, Segura said. Its such a tragic event.School officials said some of this weeks homecoming events were being postponed, including a game planned for Monday evening.The Legacy High team had played a game Friday against Chino Hills High School in suburban Los Angeles.A Monday college spirit day was modified into a Legacy day in support of the football team, senior Emily Stockhus said.Students are trying to use homecoming week to work together as a team, school to build a really strong team together, Stockhus said.---Sadie Gurman can be reached on Twitter at http://www.twitter.com/sgurman . Cheap Custom Wear . Miller reached right to deflect Mikhail Grabovskis attempt with just over 2 minutes remaining in regulation, and then made two more saves in the shootout Sunday to give the Sabres a 2-1 win over the Washington Capitals. Custom High School Jerseys . LOUIS -- Attorneys for the St. http://www.customjerseysnearme.com/custom-basketball-jerseys-136h.html . Self was acquired from the Buffalo Bandits in a trade for Alex Hill midway through last season, and made his debut in Rochester on March 16, 2013. Custom Baseball Jerseys . The Cleveland Indians, Tampa Bay Rays, and Texas Rangers all won on Sunday meaning the Rangers will host the Rays in a play-in game on Monday. Authentic Custom Jerseys . Tomas Berdych and Radek Stepanek defeated Nenad Zimonjic and Ilija Bozoljac 6-2, 6-4, 7-6 (4) on the indoor hard-court at Belgrade Arena. The victory improved the Czech pairs impressive cup doubles record to 14-1. The DealCavaliers get: Rights to forward Albert MirallesBucks get: Guard Matthew Dellavedova, cash considerations ' ' '