A Sunday morning flight out of Sacramento International Airport had to be grounded because an unwelcome passenger, a scorpion, was on board, according to the Sacramento Bee.

Over 100 passengers lined up to get on their American Airlines 10:40 a.m. flight Sunday and were told there was a an arachnid aboard the plane. The crew wasn’t sure whether to continue with the flight or not.

Ultimately the flight was canceled.

“The flight was canceled because we want passengers and crews to feel comfortable,” said American Airlines spokeswoman Leslie Scott to the Sacramento Bee.

The Boeing 747 had been in Phoenix the night before and perhaps picked up the critter there.

Most scorpions are not poisonous, only around 25 out of the around 1,500 know species can cause death to humans, according to Slate. Many of those scorpions that are poisonous, however, would have a hard time killing an adult.

In the U.S. the only scorpion that could potentially be lethal is the Arizona bark scorpion. It is the most venous scorpion in the U.S., but fatalities from its sting are rare. Children, the elderly and people with prior medical conditions are most at risk.

The plane was flown to a maintenance facility in the Dallas Fort Worth area to be fumigated.