Three such shootings have recently occurred in U.S. cinemas, including Wednesday's attack in a suburb of Nashville, Tennessee. The gunman was killed in an exchange of fire with police.
The perpetrator of the first of the three shootings is now in the sentencing phase of trial in Centennial, Colorado, where survivors and victims' families have been telling a jury about the horror of that mass killing in July 2012, in which 12 were killed and 70 others wounded.
The judge in that trial admonished jurors Wednesday to keep avoiding the news -- without specifically telling the jury about the Tennessee shooting -- in an effort to ensure a fair trial.
The jury will decide whether to sentence perpetrator James Holmes, 27, to death or life in prison.
Holmes, who has mental illness, has claimed he was suffering a schizophrenic episode at the time of the shooting. That defense earlier failed to persuade the jury, which convicted him of 24 counts of capital murder, two for each fatal victim, and other counts.
Heavily armed and dressed head-to-toe in tactical gear, Holmes opened fire in a crowded movie theater at a midnight showing of the Batman film "The Dark Knight Rises" in Aurora, Colorado.
In that attack, Holmes colored his hair an orange-red hue, making him resemble the villain The Joker as portrayed in a prior Batman film by the late actor Heath Ledger.
Lafayette, Louisiana: 'Trainwreck'
John Russell "Rusty" Houser, 59, methodically shot 11 people in a Lafayette, Louisiana, movie theater
using a handgun he legally purchased from an Alabama pawn shop.
The July shooting killed two women in the screening room that held about 25 people attending an evening showing of the new comedy film "Trainwreck."
The other nine shooting victims survived.
After the initial shooting, Houser exited the cinema through a side door and moved toward his 1995 Lincoln, but he saw a police car in the parking lot.
Houser reloaded his gun, returned to the movie theater, and fired three more bullets.
Houser eventually killed himself, firing a round to the head. He was a law school graduate with a history of mental problems.
Antioch, Tennessee: 'Mad Max: Fury Road'
An active shooter was reported Wednesday afternoon at Carmike Hickory 8 movie theater
complex in the Nashville suburb of Antioch during a showing of the new action film "Mad Max: Fury Road," authorities said.
A gunbattle ensued between police and the gunman who also carried a hatchet, pepper spray, and two backpacks, authorities said.
One moviegoer was lightly wounded by the hatchet before a SWAT team killed the suspect, authorities said. The wounded person had a superficial injury, fire department spokesman Brian Haas said.
No one has been transported to a hospital, Haas said, but three people suffered irritation from pepper spray apparently used by the suspect, who also wore a surgical mask.
The suspect, identified only as a 51-year-old man, died inside the theater.
A bomb squad was preparing to destroy the backpacks as a protective measure, officials said Wednesday.