A California family’s trip to Tijuana took a tragic turn last week when a couple and their 3-year-old son were discovered dead after a reported toxic gas leak. Joseph Núñez, Jr., his wife Maria, and their son, Jayden, were visiting relatives in Mexico when they were found dead in a room of their Airbnb on Sept. 25. The family had arrived at their residence just two days prior, according to state prosecutor Hiram Sánchez Zamora. It was not immediately clear what kind of gas they were exposed to, or where the leak had come from. A family member told a local outlet that at least eight other family members had been staying at the apartment. All of them were uninjured.

A GoFundMe page established to cover the costs of transporting their bodies back to the United States had raised more than $20,000 on Tuesday. “Our hearts are broken and we hate to ask for help but we cannot imagine leaving them in Mexico,” it reads, mentioning that any donations in excess of the $30,000 goal would be passed on to the couple’s four surviving small children. A spokesperson for Airbnb called the incident “a horrific tragedy,” and said the company would be assisting with the repatriation of the bodies. The Tijuana residence has since been delisted from Airbnb’s website.