Animal rights groups on Sunday denounced Madrid Metro officials for refusing to allow volunteers to help find and rescue a greyhound dog that got trapped in the train’s tunnels last week.

“We are sorry to inform that we found the dog dead. We can assure you that we did everything possible to rescue the animal,” subway officials posted on their Twitter account.

The greyhound had escaped from its owner on Thursday and was running mad inside the tunnels from station to station on Line 6 looking for a way out. It was last seen at the Sainz de Baranda station at around 7pm. The trapped animal caused several delays on different lines.

“It is absolutely false that they allowed any association to enter,” said a statement signed by various animal protection groups, including Hogar de Luci, Spap, Más Vida and Animal Justice.

Several members rode the metro trains to see if they could find the greyhound and some people even entered the tunnels without authorization.