GREAT MILLS, Md. (Reuters) - A 17-year-old boy opened fire at a Maryland high school on Tuesday in an attack that left two fellow students wounded, then died after a gunfight with a police officer posted there, amid a renewed national debate over gun violence in schools.

The shooting in St. Mary’s County, about 70 miles (113 km)south of Washington, came five weeks after a high school massacre in Florida and just days before a planned student-led march in the U.S. capital for tougher gun laws.

The latest bloodshed erupted shortly before 8 a.m. at Great Mills High School and lasted less than a minute, county Sheriff Timothy Cameron said, but the precise sequence of events was still being sorted out hours later.

A 16-year-old girl was in intensive care with life-threatening wounds, Cameron told a news conference. A 14-year-old boy also struck by gunfire was listed in good condition at a hospital.

The gunman was identified as Austin Wyatt Rollins, and Cameron said there was “an indication” the teenager had a prior relationship with the female student, although that was still under investigation.

The sheriff initially told reporters Rollins shot both victims with a handgun, but then said in response to questions that investigators were still uncertain who fired the shot that hit the 14-year-old.

Cameron also said it was not clear whether Rollins died after being shot by sheriff’s Deputy 1st Class Blaine Gaskill, who was assigned as the Great Mills school resource officer, or from self-inflicted gunfire.

The latest in a long string of deadly shootings at U.S. schools and colleges occurred little more than a month after 14 students and three faculty members were fatally shot on Feb. 14 at Marjory Stoneman Douglas High School in Parkland, Florida. The accused gunman, a 19-year-old former student expelled from the school for disciplinary reasons last year, was arrested and charged with 17 counts of murder.

That massacre sparked a student movement against gun violence, including a national school walkout last week that included some Great Mills students. A march in Washington by gun control activists is set for Saturday.

“We recently had a protest about school violence last week, and now this has happened,” said Kameron Norwood, 16, as he and other students waited for relatives to pick them up from a nearby high school.

Cameron said Rollins pulled out a Glock semiautomatic pistol in a hallway of the school and opened fire.

The attack ended after Gaskill ran inside and confronted Rollins, with each firing a single shot almost simultaneously.

The officer was not harmed, Cameron said. Rollins was confirmed dead nearly three hours later at a hospital.

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Rollins’ Facebook page showed he was a fan of the Dallas Cowboys football team and NASCAR auto racing, and he appeared several times on the school’s honor and merit rolls for good grades that were published in a local newspaper.

‘WE NEED MORE THAN PRAYERS’

If authorities confirm Gaskill fired the fatal shot, it may be the only known instance in which a school resource officer, or SRO, typically a law enforcement member assigned to a school, killed a student gunman during a shooting.

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In 2001, an officer shot and wounded an 18-year-old student who wounded two teachers and three other students with a shotgun at Granite Hills High School in El Cajon, California, according to the National Association of School Resource Officers.

An armed school resource officer had been on the Stoneman Douglas campus, and was criticized for failing to stop that gunman, who had an AR-15 assault-style rifle. The officer, who later resigned, said he had not been sure whether the gunfire was coming from inside or outside the school.

President Donald Trump and the National Rifle Association have proposed arming some teachers, while gun safety advocates have demanded a ban on semiautomatic rifles, among other restrictions.

Maryland’s two Democratic U.S. senators, Chris Van Hollen and Ben Cardin, called on Congress on Tuesday to pass gun safety legislation, where such measures have stalled for years.

The state’s Republican governor, Larry Hogan, said his thoughts and prayers were with the victims, but added: “We need more than prayers.”

After the Parkland shooting, Hogan proposed spending $125 million to enhance school security, including panic buttons and metal detectors, and vowed to provide an additional $50 million to hire school resource officers and counselors.