AUSTIN — The University of Texas was marking the 40th anniversary of the infamous Tower massacre with a low-key observance, lowering flags to half-staff on campus Tuesday and accepting some newly available documents related to gunman Charles Whitman.

Whitman, 25, a Texas student who was a native of Lake Worth, Fla., was killed by a pair of Austin police officers who reached him about 90 minutes after he opened fire from the 28th-floor observation deck just before noon on Aug. 1, 1966. Whitman's actions that day ultimately left 17 people dead and nearly three dozen others wounded in what at the time was the nation's worst mass shooting.