Houston Texans head coach Gary Kubiak will remain hospitalized at least 24 more hours after collapsing at halftime of Sunday night's NFL game against the Indianapolis Colts.

Kubiak, 52, hunched over and dropped to his knees at the 24-yard line while walking toward the Texans locker room and was immediately surrounded by medical personnel. He was lifted off the field on a stretcher and taken by cart to a waiting ambulance.

The Texans say that he experienced "dizziness and a light-headed feeling," but did not say what caused the problem.

"There have been so many people throughout the city and across the country that have reached out to express their love and support and we are thankful for everyone's thoughts and prayers," Texans General Manager Rick Smith said a statement released Monday. "Gary is alert, coherent and in good spirits.  He is continuing to be evaluated and monitored."

The team said Kubiak "went through a battery of tests." He is with his family and more details will be released as they are available.

Earlier, Texans defensive coordinator Wade Phillips told NBC's Michelle Tafoya that Kubiak was taken to the hospital for precautionary measures. Team representatives told NBC that the head coach never lost consciousness and did not suffer a heart attack. Phillips assumed head coaching duties for the remainder of the game.

"There was a lot of unknown," Phillips said after the game, which the Texans lost 27-24. "Everything was unknown as to what was going on and what happened to Kube."

"We were all very worried," quarterback Case Keenum said. "When we went back out they told us he was ... stable. We were all upset about that but trying to stay focused at the same time."

Kubiak's medical scare came one day after Denver Broncos head coach John Fox revealed that he would need aortic valve replacement surgery after suffering a dizzy spell while golfing near his home in Charlotte, N.C. The surgery would require Fox to spend at least a month away from the team.

Fox had been told earlier about his heart condition and was hoping to put off the operation until February. As part of his trip to North Carolina over the Broncos' bye week, he met with his cardiologist in Raleigh and was told to seek medical attention immediately if he felt any discomfort.

At the time of the episode, the Texans held a 21-3 lead over the Colts, led by Case Keenum and Andre Johnson, who connected for three touchdowns, including two in the first quarter. However, the Texans only scored 3 points in the second half as Indianapolis rallied for a 27-24 victory.

Kubiak has long been known as a top offensive coach, mentoring quarterbacks in Denver under Mike Shanahan and now Matt Schaub -- and Case Keenum -- in Houston. Kubiak has had no known public health problems.

Kubiak was hired in 2006, along with general manager Rick Smith, after the Texans finished a franchise-worst 2-14. Smith spent 10 years with Kubiak while the coach was offensive coordinator of the Broncos. Smith was Denver's defensive assistant for four seasons before moving into the front office for his last six years with the Broncos.

The pair has helped transform the Texans, which began play in 2002, from league laughingstock to contender.  The team went 6-10 in their first year and 8-8 in each of the next two seasons. Expectations were high in 2010 after Houston finished at 9-7 for its first winning record in 2009. But the Texans instead fell to 6-10, which led to many fans calling for Kubiak's firing.

His original contract was due to expire after the 2010 season, but owner Bob McNair has stepped up to keep Kubiak and defended him several times amid the bumps. Among recent departures were assistant head coach Alex Gibbs (for Seattle) and offensive coordinator Kyle Shanahan went to join his father, Mike, in Washington.

Kubiak hired former Denver offensive coordinator Rick Dennison to replace Shanahan and former Atlanta offensive coordinator Greg Knapp to become Houston's quarterbacks coach. Dennison worked on the Broncos' staff during Kubiak's 11 years as Denver's offensive coordinator, and Knapp coached Schaub for three seasons with the Falcons.

The highest-profile assistant brought to Houston was Phillips, the veteran son of Bum Phillips and a former head coach in Dallas.

Last year, the Texans announced contract extensions for both Smith and Kubiak, rewarding them for taking the team to the playoffs last year for the first time. Kubiak's three-year agreement has him under contract through 2014.

McNair said at the time he offered Kubiak a four-year deal, but the coach preferred to make it for three.

Kubiak made his mark as Denver's offensive coordinator under Shanahan, winning two Super Bowls. An eighth-round pick out of Texas A&M, he spent nine years as John Elway's backup. He finished his career 4-1 as a starter, all in emergency relief of Elway.

The Associated Press contributed to this report.