Students sit outside Woodrow Wilson High School in June 2014 in Washington, DC. (Matt McClain/The Washington Post)

In the three days since a gun was found on campus, Wilson High School has increased security staff, repaired exterior doors and instituted daily “sweeps” of the building, according to a letter Principal Kimberly Martin sent to the school community Friday.

A new “special police officer” and an additional security staff member have been assigned to the school, the city’s largest with more than 1,800 students. Martin said increased security staff are monitoring all exterior doors, some doors are being repaired and surveillance cameras are being assessed to maximize coverage.

School staff members also are rearranging duties to make sure that the video cameras are routinely monitored, she said.

“Times of crisis often serve as opportunities to forge responsive practices, institute better policies, and to garner support for changes and improvements,” Martin wrote in the letter.

A semiautomatic handgun was recovered in a Wilson classroom Tuesday morning. According to a police report made public Wednesday, one student flashed the weapon in a hallway and then put it into another student’s backpack. The report says that another student saw the handoff and notified the classroom teacher, who called police.

The incident frightened the school community and raised questions about how the gun could have been carried into the building. The main entrance has metal detectors and X-ray machines.

Lt. Sean Conboy, a D.C. police spokesman, said investigators had not yet determined how the gun got into the high school.

Many students and parents have said there are less-secure places through which people can enter the building — in particular, using additional exterior doors that are not guarded and can be opened easily from inside the building or after school hours, when people said they can come and go freely.

Martin outlined a detailed response to better securing the campus. Going forward, she said, all doors will be locked until 8 a.m. Students who want to enter earlier will need to be escorted by an adult supervisor, such as a coach or a teacher.

Security officers will sweep the building at the end of the day, at 3:45 p.m. and 4:15 p.m., and escort unsupervised students out of the building. A school security staff member will be stationed at the front door each evening after security officers who are contracted through a private firm leave.

Michelle Lerner, a spokeswoman for D.C. Public Schools, said most school security staff are managed through the city’s police department, which contracts some responsibilities to a private company, AlliedBarton Security Services. AlliedBarton employs tens of thousands of security officers across the country.

The school put signs on doors to notify people that there are security cameras and alarms, and additional police officers will be available to help students travel safely to and from school, Lerner said.

Anita Seline, a parent at the school, said that this week’s incident was “scary” but that she is glad to see the principal is “taking these steps to prevent something worse from happening.”

Wendy Feliz,whose son is a senior at Wilson, said the school system needs to do everything it can to keep students safe, but at the end of the day, the incident at Wilson is a reflection of inadequate gun control nationwide. The issue attracted renewed attention and debate after a mass shooting of health department workers in San Bernadino, Calif., on Wednesday.

“This is one piece of a wider problem in this country,” she said. “Teenagers in high schools should not have access to guns. We are in the back yard of Congress, and we need to do something about this.”