Americans have donated about $350 million to help the victims of hurricanes Harvey and Irma.

But in times of disaster, it is easy to donate to the wrong charity or get scammed out of money. Experts were warning good Samaritans to beware of “fly-by-night” charities that promised bogus disaster relief.

“You want to research the charity that you’re dealing with,” says Melissa Companick with the Better Business Bureau. “Does that charity have a physical presence on the ground? Where they there before the disaster hit? Do they have people there that can actually help with immediate needs?”

Companick says that one simple way to check out a charity is to go to a website like CharityNavigator.org or Give.org. These websites provide a list of approved hurricane charities.

“No charity can ever really say that 100 percent of your donation is going to the relief effort,” Companick says. “A high percentage should, absolutely, but it’s just not feasible that 100 percent can go.”

Experts say to also be skeptical of any claims that seem too good to be true.