While Dallas police were not immediately available to provide additional details, it’s a rare occurrence that a police department would use a disposal robot to set off a bomb. The robots are designed to dismantle and defuse bombs, not wheel bombs into situations. Nor are these cheap machines; some cost upwards of $100,000.

It’s worth noting that these robots are not autonomous machines able to act on their own accord. They are remote-controlled vehicles that must be operated by a human. Here’s an example of one in action:

The US government has been using automated machines to take out targets for years—think drone strikes in the Middle East. Last year, North Dakota even became the first state to legalize police officers’ use of drones fitted with weapons such as tasers and pepper spray. Last night’s action likely won’t be the last time a remote-controlled device is used to take out a human in the US, but it raises interesting ethical questions about where bomb robots fit in police forces’ increasingly militarized approach to protecting the public.

📬 Sign up for the Daily Brief

Our free, fast, and fun briefing on the global economy, delivered every weekday morning.