Houston, Texas - A fleet of 52 empty yellow school buses arrived outside Republican Senator Ted Cruz's Houston office on Thursday, representing 4,368 US children's lives taken by gun violence since 2020.

The buses, whose seats were all empty, carried special items from victims who have died in school shootings, donated by the families. The bus caravan reportedly stretched a mile long.

The action was organized by Change the Ref, an organization started by the parents of Joaquin Oliver, who was killed in the school shooting in Parkland, Florida, in 2018.

Joaquin's father, artist Manuel Oliver, told Buzzfeed he designed the project "partially with the intention that some people will think this is truly an NRA museum."

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In the wake of several recent mass shooting, including the massacre in Uvalde, Texas, many powerful politicians have been slammed for accepting donations from the National Rifle Association (NRA).

"We’re going after the money," Oliver explained. "These leaders are not loyal to the Second Amendment. They’re loyal to the gun industry and manufacturers, who protect them. And there’s lots of messages that supporting gun control is not patriotic. It’s corrupt, and I wanted to find a graphic way of showing them what the impact really is."

Ted Cruz received $176,284 in contributions from the NRA in 2019 alone, according to data from Brady. He also gave a speech at the NRA convention, held in Houston in May – just days after the Uvalde shooting.

Joaquin Oliver's parents also hand-delivered a letter from their deceased son to Ted Cruz's office.

In the letter, which was written in 2013 after the Sandy Hook massacre and just five years before Joaquin was killed, the then 12-year-old expresses frustration at opposition to background checks before gun sales.

"He was a kid writing this letter. I was really impressed when I read it. We’ve been keeping it, our little letter to remind us about what we’re fighting for," Manuel Oliver told Buzzfeed.

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"My son knew, at 12 years old, what to do better than Ted Cruz. I want [Cruz] to read that with his own eyes."

Oliver handed the letter over to a member of Cruz's staff, who said the senator was currently at the Capitol.

Ted Cruz may have been the first stop on the bus tour, but he may not be the last. "If you’re a senator and you believe the things that are happening are okay, look out for a yellow school bus that will be outside your office," Oliver warned.