DENVER, the United States, April 18 (Xinhua) -- The dark, low-lying clouds that hung over southwest Denver Thursday morning reflected the somber mood of students, who returned slowly to school after 48 hours of fear.

"It is scary we're in a situation where this is a common thing," said Calvin Ferrell, a senior at Mullen High School, who went to the Columbine Library on Wednesday to study when his Catholic college-prep school was closed.

More than 20 Denver schools were closed Wednesday and thousands of teenage students stayed home while police conducted a massive search for a young Miami woman.

Sol Pais, 18, posted threatening comments online Sunday, and then flew to Colorado's capital Monday when she purchased a shotgun and ammunition near Columbine High School, where 12 students and a teacher were gunned down 20 years ago.

Her body was found Wednesday by authorities in a wilderness area 46 miles west of Denver in the Rocky Mountains. On Thursday, it was confirmed she had committed suicide.

"We are thankful to law enforcement for their swift response," said Colorado House Representative Tom Sullivan, as police responded to a tip from a rideshare driver who identified Pais and brought them to her location.

"It is a scary something like this can happen so quickly," said Marissa Bruno, a senior at nearby Dakota Ridge High School.

"It makes me feel sick that this whole situation happened. It is so important to look at mental health," she told Xinhua.

Sullivan, a Democrat elected in 2018 by conservative voters in southeast Denver, last month pushed a landmark "red flag" piece of legislation through Colorado's state House that might have helped law enforcement respond faster to Wednesday's terrifying incident.

MENTAL HEALTH

"We need to improve access to mental health resources across our country," Sullivan told Xinhua Thursday, a common link between the mass murders that have inundated America during the past seven years.

In 2012, Sullivan's son Alex was killed in a mass shooting at the midnight showing of a nearby Batman movie that left 12 dead and 70 injured.

Columbine High School is located in Littleton, a conservative southwest suburb of Denver, where Republican politicians and the National Rifle Association (NRA) are popular.

"I consider myself very conservative - when I turn 21, I will openly carry a gun," said Brevin Welch, 20, a college student who lives close to Columbine High.

"But I have no problem with more background checks," he told Xinhua. "They make sense."

A majority of Americans want a better background check system - that failed to identify Pais when she bought her gun Monday - but the powerful NRA opposes improvements in the way a person's dangerous mental health or instability might be spotted.

The NRA is a special interest group that boasts 5 million members and has a track record of influencing and bankrolling conservative members of U.S. Congress who oppose any gun control efforts.

"Times are changing in America - people want to protect their families, they want to protect their children, and that means supporting sensible gun control measures and opposing the NRA," gun control advocate Sandy Phillips told Xinhua.

Even conservative voters are getting fed up with the NRA's rabid defense of guns, according to Phillips, and people in the neighborhood surrounding Columbine High seem in agreement.

TIME OUT

"We need a waiting period," said Bruno, 18, about the time between a person's application for a gun and the time they receive the weapon.

"She (Pais) might have been able to get help if there was a waiting period - we need better background checks," she told Xinhua.

Megan Boyd, 34, was sitting at a park bench Thursday, across the street from Columbine High, eating lunch with her twin five-year-old sons and three-year-old baby daughter.

"At a bare minimum, we need a waiting period," Boyd told Xinhua. "They need to put controls on gun purchases, especially in regard to mental illness," she added.

"Studies show that if a person considering suicide person can get through the first day or two, they will many times change their minds," said Pro-NRA Welch, a psychology major at Metro State University.

Ferrell and his younger brother Jacob, 16, also a Mullen high student, agreed that background checks need tightening.

Both young men told Xinhua that assault rifles should be banned to the American public.

"Common people don't need them for hunting, they are designed to kill a lot of people," Calvin Ferrell said.

Automatic rifles have been used in a number of mass murders, including the 1999 Columbine and 2012 Aurora theater shootings.

Last month, an estimated half of Colorado's 64 county sheriffs said they will not obey Sullivan's new "red flag" bill, and almost all oppose a ban on assault weapons, another reasonable effort to curb America's gun killings.

But not Pitkin County Sheriff Joe DiSalvo, who calls automatic weapons "guns intended for use in a military theater and designed to kill many people quickly."

"They should not be allowed for public use," he told Xinhua.