GREAT MILLS, Md. (AP) — In the latest school shooting in America, the gunfire was over and done with in less than a minute.

This time, the shooter, a 17-year-old student, was killed. Authorities said a 16-year-old girl who had some type of relationship with the shooter was critically injured, and a 14-year-old boy also was wounded.

The school resource officer who responded inside of 60 seconds and fired off a shot at the attacker was praised as a hero.

The violence erupted as classes were beginning Tuesday at Great Mills High School in southern Maryland, in a community where many families have military ties, with parents working at the Patuxent River Naval Air Station or Andrews Air Force Base.

It came a month after 17 people were killed at a Florida high school, and intensified calls for Congress to act on gun violence at schools.

It wasn’t immediately clear in Tuesday’s attack whether the shooter — identified as Austin Rollins, a student at Great Mills — took his own life or was killed by the officer’s bullet, nor was it clear how the 14-year-old boy was wounded, St. Mary’s County Sheriff Tim Cameron said. But the sheriff credited the officer with preventing any more loss of life.

The officer, Deputy First Class Blaine Gaskill, a six-year veteran with SWAT team training working his first year inside the high school, responded quickly, Cameron said.

Within a minute after Rollins fired his first shot, Gaskill had responded and fired a shot of his own. Cameron said Gaskill fired his weapon simultaneously with a final shot fired by Rollins. Cameron said he did not know whether Rollins was intending to shoot himself or Gaskins, who was unharmed.

“He had to cover significant ground,” Cameron said of Gaskill’s response. “The premise is simple: You go to the sound of gunfire.”

Authorities didn’t release a motive, but said they believe the girl and Rollins previously had a relationship.

Police did not identify the victims, but the family of 16-year-old Jaelynn Willey, a sophomore at Great Mills, confirmed she had been shot.

Jaelynn is one of nine siblings, according to a statement from the family, and a member of the swim team.

“Jaelynn is an amazing young lady, whose peaceful presence and love of her fellow students and family is known throughout her Maryland-based school,” the family statement said.

A fundraiser for the family on the youcaring.com website had already raised more than $25,000 by Tuesday evening.

At a vigil Tuesday night in nearby Lexington Park, religious leaders from different denominations prayed together for the victims. On a “prayer wall” at The Church of the Ascension, people wrote prayers in chalk. One said: “Lord, help the parents of the shooter to find hope and peace in you.” Another said: “Please choose love.”

Politicians responded swiftly with calls to change laws and policies.

“We sympathize. We empathize. We have moments of silence. But we don’t have action,” said the No. 2 U.S. House Democrat, Steny Hoyer, who represents the area in Congress. “Wringing our hands is not enough.”

In this case, it appeared Rollins possessed the gun illegally. In Maryland, a person must be 21 to possess a handgun, unless carrying one is required for employment. It’s unclear how Rollins obtained the weapon.

Attempts to reach his family were unsuccessful.

One of the shooter’s friends, 14-year-old Jordan Hutchinson, and his mother dropped off a condolence card at the Rollins home.

Jordan recalled meeting Austin five years ago during a snowstorm, and building snow forts together.

“Austin was a nice kid. We did sleepovers all the time,” he said.

Students endured a lengthy lockdown, cowering inside classrooms and a locker room while officers worked to make sure there were no more threats on campus. Police eventually kicked in the locker room door, said Ziyanna Williams, a 14-year-old ninth-grader.

“They came in with guns, and they probably thought there might be another shooter, of course,” she said. “About an hour or two later they came — more police came — and told us they would search us and search our bags and stuff.”

Maryland’s Senate joined the House on Monday night to ban bump stocks, which enable a semi-automatic rifle to mimic a fully automatic weapon.

Republican Gov. Larry Hogan, meanwhile, accused the Democrat-led legislature of failing to take action on “one of the most aggressive school safety plans in the country.” It commits $125 million for capital improvements such secure doors and windows, metal detectors and security cameras. It also includes another $50 million annually to pay for school resource officers, counselors and technology.

Hogan said “it’s outrageous that we haven’t taken action yet,” with less than three weeks left in the session.

House Speaker Michael Busch, a Democrat, said legislators have “every intention” of passing legislation to make schools safer.

This weekend, students across the country plan an anti-gun violence march on the nation’s capital. James Scott Smith, superintendent of schools in St. Mary’s County, called Tuesday’s shooting “our worst fear.” He and other authorities said there were no obvious warning signs that Rollins posed a danger.

“If you don’t think this can happen at your school, you are sadly mistaken,” he said.

This undated photo provided by the Willey family shows Jaelynn Willey. A teenager armed with a handgun shot and critically wounded Willey inside a Maryland school on Tuesday, March 20, 2018, and the shooter was killed when a school resource officer confronted him moments after the gunfire erupted. A third student was in good condition after he was shot. (Courtesy of the Willey family via AP)

This undated photo provided by the St. Mary’s Sheriff’s Office, shows Deputy First Class Blaine Gaskill, a school resource officer who engaged a shooter at Great Mills High School in Great Mills, Md., on Tuesday, March 20, 2018. It wasn’t immediately clear whether the shooter took his own life or was killed by the officer’s bullet, St. Mary’s County Sheriff Tim Cameron said, but the Gaskill was credited with preventing any more loss of life. (St. Mary’s Sheriff’s Office via AP)