The Texas mass shooting that had left 26 dead and was dubbed as the deadliest in modern history of the country has left many Americans in shock.

The lone gunman, identified as Devin Patrick Kelley, took the life of parishioners attending church at First Baptist Church in Sutherland Springs, with the victims' age ranging from 17 months to 77 years old. Kelley was shot three times, two by a citizen on the torso and leg, and the third one, believed to be self-inflicted, on the head. Authorities found the killer dead on his vehicle.

Meanwhile, celebrities had expressed their grief through social media. "Oops! I Did it Again" singer Britney Spears took to Twitter to air her concern. "My heart breaks over the news coming out of Texas. My prayers are with the Sutherland Springs community," Spears wrote. Golden Globe Award winner Reese Witherspoon also expressed her sadness over what transpired.

"You Raise Me Up" singer Josh Groban also shared on Twitter his disbelief of the killings. "Spotlight" star Mark Ruffalo mourned with the victims' families, and reminded them that "[w]e're all in this together."

Some celebrities also denounced the incident and called for the gun control laws to be passed. Lady Gaga said she would pray for the victims' families, as well as for gun control. The 70-year-old author of the "Pet Sematary," Stephen King, pointed to the importance of gun control measure by asking, "How many more have to die before we enact sane gun control laws?"

The gunman apparently had a history of violence, including sending threats to his mother-in-law early on Sunday, just before the shooting took place. Aside from this, he was denied a gun license but was able to buy in April last year a Ruger AR-556 rifle after circumventing background checks. This lapse was attributed to the US Air Force's failure to submit documents of the gunman's violent history to the Federal Bureau of Investigation.