A group of activist nuns filed an unusual shareholder lawsuit to pressure gun maker Smith & Wesson to drastically change the way it markets, makes and sells its popular version of the AR-15 rifle.

The first gunshot cracked through the air just after 1 a.m.

Then came another shot, and another. They kept coming, again and again, each shot thundering across downtown Dayton, Ohio. In just half a minute, more than three dozen gunshots echoed through the crowded streets.

A gunman who killed four people at a Tulsa hospital Wednesday targeted a doctor who had treated him and bought the AR-15-style rifle used in the shooting on the day of the attack, police said.

Michael Louis was armed with a rifle, which he had purchased at 2 p.m. Wednesday, and a handgun when he went to St. Francis Hospital shortly before 5 p.m., officials said.

Two orthopedic surgeons, a medical office staffer and a patient visitor were killed in a mass shooting Wednesday on the campus of Saint Francis Health System in Tulsa.

The gunman reportedly was able to purchase a semi-automatic rifle just hours before the slayings targeting a specific physician, according to investigators.

Mayor G.T. Bynum and officials from Saint Francis Health System and Tulsa Police Department offered more details Thursday on the shooting that left four innocent people dead, as well as the gunman.

A deranged gunman with a rifle and a handgun who killed four people at an Oklahoma medical building targeted a doctor who previously operated on him “and anyone who got in his way,” authorities said Thursday.

The gunman, identified as Michael Louis, opened fire at about 5 p.m. Wednesday at an orthopedic office on the second floor of the Natalie Medical Building at Saint Francis Health System in Tulsa, Police Chief Wendell Franklin told reporters at a press conference.

The gunman who killed 21 children and teachers at a Uvalde, Texas, elementary school last week bought two AR-15-style semi-automatic rifles days after his 18th birthday. A House bill being voted on this week would have prevented the sale by barring anyone under 21 from purchasing that type of firearm nationwide.

After Tuesday’s school shooting in Uvalde, Texas left 19 children and two adults dead, we wondered how difficult it was to order a DDM4V7, one of the two rifles the gunman bought a few days after turning 18 years old, according to reports.

The answer: Five clicks.

The AR-15-style weapon, made by Georgia-based Daniel Defense, sells online for $1,870, plus tax. Shipping to a local gun shop is free.

Families of Sandy Hook victims reached a $73 million settlement Tuesday in their lawsuit against Remington Arms, manufacturer of the AR-15 semi-automatic rifle used to kill 20 kids and six staff members in the 2012 massacre.

The nine families brought a class-action suit in 2014 against Remington Arms, which made the weapon used in the mass shooting, claiming the gun-maker sought to sell the military-grade weapon to the mentally ill.