A drone delivery program in Switzerland has been suspended indefinitely after one of the vehicles crashed just 50 yards away from a group of children. Frankfurter Allgemeine Zeitung reports (via IEEE Spectrum) that the 10-kg (22-pound) drone, capable of carrying up to 2-kg of cargo, encountered an issue during a flight in Zurich in May. Although the drone was equipped with an emergency parachute, it managed to cut the connecting cord during its emergency landing, resulting in an uncontrolled crash. Nobody was injured.

The incident comes as multiple regulators are easing flight restrictions to allow commercial drone deliveries. Google’s Wing has been granted regulatory approval to make deliveries in the US and Australia, and in the US the FAA is considering new rules that would allow drones to fly over crowds and at night.

This is the second crash suffered by the Swiss drone delivery program this year. Back in January one of the drones, which is operated by US drone startup Matternet in collaboration with Swiss Post, suffered an issue with its GPS system, causing it to make an emergency landing. However, in that case the drone’s parachute successfully deployed, and the landing was controlled. The delivery program was suspended until April.

The crash is the second that’s occurred this year

It’s currently unclear what exactly caused the May crash or if the drone was carrying cargo at the time. Swiss Post’s preliminary investigation suggests that wind may have been to blame. Despite the crash’s close proximity to children, TechCrunch notes that the incident occurred over a forest, rather than a populated area or a school.

In response to the crash, Swiss Post has asked Matternet to make several changes to the safety features of its drones. It wants each drone to be connected to its parachute by two ropes rather than one, it wants the ropes to be reinforced with metal braiding, and it wants the drone’s existing emergency landing whistle to be louder. Swiss Post said that it is establishing a board of experts to advise the postal service on the safety aspects of drone delivery services.

Matternet provided a statement to Spectrum IEEE in which it said that it had never seen a failure like the one that its drone experienced in May and that the drone’s parachute system had never failed before. “A failure of the parachute system is a clear failure of our safety mechanisms and we are taking all the appropriate measures to address it,” the company said, adding that it intends to restart operations once Matternet, Swiss Post, the Swiss Federal Office of Civil Aviation, and the company’s hospital customers in Switzerland are satisfied that the “appropriate mitigations” have been applied.

The Swiss delivery program has been running in Switzerland since 2017 where it delivers lab samples such as blood tests flown between hospital facilities, clinics, and labs. IEEE Spectrum notes that the service was operating in three Swiss cities until its suspension, and had made around 3,000 successful flights as of January.

Matternet doesn’t just operate in Switzerland. In the US, UPS partnered with the drone startup to deliver medical supplies earlier this year in North Carolina.