The letter, published by The Baltimore Sun, urged Trump and Congress to support gun control measures and to reject Trump’s proposal to arm teachers.
The schools called for a more “robust system of registration and background checks,” especially for "military-style" assault weapons or guns capable firing a “vast number of deadly shots."
The letter came on the same day as the National School Walkout, where thousands of students across the country left class temporarily to demand action on gun violence.
Many students have been advocating for Trump and other Republican lawmakers to implement gun reform following the deadly Parkland, Fla., school shooting where 17 people were killed on Feb. 14.
Trump unveiled his gun reform proposals on Sunday meant to “harden” schools, which included arming teachers, amping up the nation’s background check system and approving $50 million for school safety improvements. The administration's proposals include banning bump stocks, a device used to modify semi-automatic rifles to fire at faster speeds.
Trump's proposals made no mention of raising the minimum age for firearm purchases from 18 to 21, something Trump expressed support for last month and many student advocates have called for.
Sen. Dianne FeinsteinDianne Emiel FeinsteinLawmakers in both parties to launch new push on Violence Against Women Act Domestic travel vaccine mandate back in spotlight Biden, lawmakers mourn Harry Reid MORE (D-Calif.) said Trump “completely caved” on the idea after meeting with gun lobbyists and the National Rifle Association.