On Tuesday morning, a bomb went off outside of the office building that houses the Colorado Springs, Colorado, branch of the NAACP. Although authorities have not said whether the NAACP was targeted or that the attack was an act of terrorism, the bombing is a reminder of the kind of attacks that civil rights groups have faced for decades. After the bombing, the Twitter hashtag #NAACPBombing took off to highlight what many saw as the lack of media coverage of the event. Fueling this frustration is a sense that the media has historically ignored stories of specific concern to African Americans, but there’s also a serious worry born out of the long history of violent attacks against civil rights organizations. Bombings against black homes and churches in Birmingham, Alabama, were so common during the early 1960s that the city had gained the derisive nickname “Bombingham.” But Birmingham was far from alone in this violent era against the Civil Rights Movement. Racist attacks targeted civil rights groups before Martin Luther King Jr. talks on phone after encountering a protest against the Freedom Riders in Montgomery County, Alabama. (Express Newspapers via Getty Images) Ever since the NAACP’s founding in 1909, the organization has been a recurring victim to attacks. On Christmas Day 1951, Harry Moore, who founded an NAACP branch in Brevard County, Florida, was killed by a bomb placed under his bed. He was the first NAACP official killed in the civil rights struggle, according to PBS. Several KKK members were suspected in the incident, but the case remains unsolved. These kind of attacks against the NAACP would continue throughout the decades, as Time magazine reported. In 1963, a white supremacist shot and killed Medgar Evers, a field secretary for the NAACP, outside his home. In 1989, a package containing a bomb killed Robert Robinson, legal counsel for the NAACP in Savannah, Georgia; other packages were sent to the NAACP branch in Jacksonville, Florida, but authorities caught the packages before they did harm. These types of attacks extended to other civil rights groups as well. Freedom Riders who traveled to the Deep South to purposely defy segregation laws were regularly attacked. When the first Freedom Riders arrived in Alabama in 1961, a mob chased down the bus and threw a bomb into it, causing the vehicle to burst into flames. The riders escaped the bus, but the mob brutally beat them. These attacks continued during later Freedom Rides. But the recurring violence brought more international attention to the cause, eventually bringing hundreds of new participants. The Birmingham church bombing killed four black girls The 16th Street Baptist Church in Birmingham where a bomb killed four girls in 1963. (Universal Images Group via Getty Images) Civil rights groups during the early 1960s actively targeted Birmingham for protests, knowing that the city — and the state it resided in — was a hub for white supremacy groups and supporters of segregation. The backlash was fierce: KKK members routinely called in bomb threats — and others exploded homemade bombs — to disrupt civil rights meetings and church services. The anger eventually led to one of the most well-known terrorist attacks against the Civil Rights Movement. On September 15, 1963, a bomb detonated at the predominantly black 16th Street Baptist Church in Birmingham. About 200 people were in the building, many attending Sunday school service, according to History.com. Four black teenage girls died, and at least 20 others were injured. News wire service UPI described the aftermath in 1963: Parts of brightly painted children’s furniture were strewn about in one Sunday School room, and blood stained the floors. Chunks of concrete the size of footballs littered the basement. The bomb apparently went off in an unoccupied basement room and blew down the wall, sending stone and debris flying like shrapnel into a room where children were assembling for closing prayers following Sunday School. Bibles and song books lay shredded and scattered through the church. In the main sanctuary upstairs, which holds about 500 persons, the pulpit and Bible were covered with pieces of stained glass. It was the the fourth bombing in Birmingham in four weeks and the 21st in eight years, UPI reported at the time. Up to that point, none of the bombings had been resolved in court. It took decades to deliver justice in Birmingham President Barack Obama designates Congressional Gold Medal to victims of Birmingham church bombing. (Mike Theiler / pool via Getty ImagesGetty Images News) With many of these cases, civil rights groups criticized authorities for dragging their feet during investigations. Even the investigation into the Birmingham church bombing, the most high-profile of the cases, didn’t lead to justice for decades. According to the FBI, Robert Chambliss was convicted to life in prison in 1977, Bobby Cherry and Thomas Blanton were indicted in 2000 and later convicted to life in prison, and a fourth suspect, Herman Cash, died in 1994 before he could face trial. For some, the feeling of neglect remains. When Congress in 2013 commemorated the victims of the Birmingham church bombing, some of the survivors and relatives told the Associated Press they weren’t interested. Sarah Rudolph said she wanted compensation for the injuries she suffered, including a lost eye, and the death of her sister, who was one of the girls killed. “We haven’t received anything, and I lost an eye,” Rudolph told the AP. “It’s a smoke screen to shut us up and make us go away so we’ll never be heard from again.” Read more: NAACP office building in Colorado Springs bombed.