Almost 50 years ago Charles Whitman stood on top of the tower observation deck at The University of Texas at Austin.

On Aug. 1, 1966, Whitman murdered 14 people and wounded more than 30 in 96 minutes from the top of that deck — the biggest mass murder in U.S. history at the time and the nation's first campus shooting.

Thursday night, five police officers were killed and seven were injured in a civilian sniper attack in Dallas, bringing attention to civil unrest and a country that has become continually more divided — citizens pitted against police officers — after the deaths of Alton Sterling and Philando Castile.

And for three professors at The University of Texas at Austin, keeping guns away from the classroom is essential now more than ever.

The professors have filed a federal lawsuit hoping to block the state law that would allow licensed gun holders 21 or older to bring handguns into classrooms and buildings throughout one of the nation's largest universities, according to the Huffington Post.

According to TPM LiveWire, Senate Bill 11 (Campus Carry) will take effect on Aug. 1, hitting the 50-year anniversary of Whitman's UT tower shooting.

“The fact that it is coming into effect on the 50th anniversary of Charles Whitman has a resonance with a lot of people and serves to heighten for a lot of people a sense of what guns on campus can be, and the harm that guns on campus can do,” Steven Goode, a UT law professor, told My Statesman. “Obviously, Charles Whitman was not carrying a concealed handgun. The law that was enacted wouldn’t have changed anything with regard to what happened with Charles Whitman.”

University officials said they were reviewing the lawsuit. As the Huffington Post noted, Gov. Greg Abbott has said the Campus Carry law "could prevent mass shootings because someone with a licensed concealed weapon could confront a gunman."

Mass shootings have become familiar in the U.S., with 104 killed and 226 injured in June 2016 alone, along with 188 school shootings in America since 2013, according to the Mass Shooting Tracker — sparking debate about gun control.

According to the Texas Tribune, in the lawsuit, the professors explained they teach courses that touch on emotional issues, including gay rights and abortion — and the possibility of students carrying guns could restrain class discussion, which would be a violation of the First Amendment.

"If the state is to force them to admit guns into their classrooms, then the officials responsible for the compulsory policy must establish that there is a substantial reason for the policy and that their regulation of the concealed carrying of handguns on college campuses is 'well-regulated.' Current facts indicate that they cannot do so," the suit read.

Email: mmcnulty@deseretnews.com

Twitter: megchristine5