Hundreds have lined up to do their part at Texas blood drives in the wake of Sunday's church massacre.

Texans eager to help stood alongside South Texas Blood and Tissue Center buses parked outside Connally Memorial Medical Center Monday, patiently waiting their turn to donate.

Watch: Hundreds Donate Blood in the Wake of Las Vegas Mass Shooting: 'I Wanted to Do Something Right Now'

It was a symbol of hope for many in the tiny town of Sutherland Springs, where at least 26 people were murdered and 20 injured, some critically, during Sunday services at the town's First Baptist Church.

In the hours after police say Devin Patrick Kelley stormed the church armed with a semi-automatic, University Health officials in San Antonio told reporters that blood supplies were "dangerously low" even before need spiked following the attack.

"With the tragic shooting in Sutherland Springs on Sunday, donations are absolutely crucial," the San Antonio Current reported.

Donors lined up at the Floresville hospital included Naimah Ahmed of San Antonio. 

"As a Muslim and Ahmedi Muslim, this, our first act…should be that we serve humanity," Ahmed told APTN. "That's what we believe in. We are ready to donate, we are ready to serve. We want to be with these people we want to feel their sorrow and this sad situation. It's very tragic."

Floresville mother Katherine Hanrahan also donated.

"I'm a mom and community member really," Hanrahan told APTN. "I have children and I can't imagine the devastation and heartbreak they're going through. And I want to do anything I can. I can do this, so I am. That's it."

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In a post on Twitter, the South Texas Blood and Tissue Center pleaded specifically for those with Type O blood to donate.

"The supply of O negative — which is needed most during traumas — is low," the center's parent company wrote in a Twitter post Monday.