After a 21-year-old gunman killed 20 and injured at least 26 people at a Walmart in El Paso, Texas, efforts of community goodwill continue to flourish.

Hundreds of people took action and responded to social media calls by both the city of El Paso and the El Paso Police Department to donate blood and showed up to nonprofit blood donation centers ran by Vitalant in and surrounding the city.

Outside the Vitalant in El Paso, social media videos showed a line of hundreds of people gathered to donate blood. The line, some witnesses reported, wrapped around the facility and into the parking lot.

Vitalant confirmed that 240 units of blood were donated today.

Sandra Ramirez, a reporter at El Paso news station KTSM-TV, tweeted out images of individuals passing out slices of pizza and bottles of Gatorade and water to donors waiting in line.

Though the Vitalent facilities in both West El Paso and nearby in Las Cruces, New Mexico have closed, the facility is opening its doors again tomorrow.

All nearby facilities will be open Sunday from 8 a.m. to 5 p.m. MT to accommodate those who want to donate after the shooting. They will continue to take donations through the week.

Normal operating hours today were extended in the wake of the shooting, and Vitalant is usually closed on Sundays. They are also taking donations at the nearby Abundant Living Faith Center from 9 a.m. to 5 p.m.

Individuals can make appointments by visiting the BloodHero website or making a call at 1-877-258-4825.

"We can take no more donors today, and we do not want you to waste your time," said a Facebook post from the El Paso Vitalant published Saturday.

"We will need your precious donation going forward for ongoing victim needs and to replenish supplies."

Lyft will be offering free rides worth up to $15 each way to blood donation centers with the code ELPRELIEF19.

Contributing: Sarah A Dueñas and María Cortés González, El Paso Times. Follow Joshua Bote on Twitter: @joshua_bote