There are long lines to donate blood in Orlando communities following the mass shooting and terrorist attack in Orlando, Florida early Sunday morning where at least 50 people were killed and 100 injured at Pulse Nightclub.

Huge line at W. Michigan blood bank right now. Urgent need for O Negative, O Positive, AB Plasma blood pic.twitter.com/D9PPyi6wD5 — Matt Grant (@MattGrantFOX46) June 12, 2016

Line to donate blood at Orlando bank wrapped around the block #OrlandoNightclubShooting pic.twitter.com/IpF6XUY6yp — Linzie Janis (@LinzieJanis) June 12, 2016

https://twitter.com/Breaking911/status/742011684781428736

The shooter, Omar Mateen, was from Port St. Lucie, Florida and was a Muslim who was born in New York to parents of Afghan origin. The FBI investigated Mateen in 2013 and 2014, but ultimately closed the investigation, according to Fox News. Fox News also reports Mateen was a registered Democrat in Florida with a state firearms license.

Orlando officials called for blood donations following the attack.

“Blood is a wonderful gift. You can work through the local blood banks to donate, and that would be a tremendous help,” Dr. Michael Cheatham declared during a press conference on Sunday morning.

OneBlood, which is a nonprofit clinic located in Orlando, is calling for donations from all donors — even gay men, according to The Hill.

“There is an urgent need for O Negative, O Positive and AB Plasma blood donors following a mass shooting in Orlando, Florida,” OneBlood posted on Facebook. “The need for blood continues. All eligible O Negative, O Positive and AB donors are urged to please donate today.”

“Donors will be given full blood screening. But they are not turning people away from donations,” OneBlood posted on Twitter.