Hawaii Duck Tours remains grounded until further notice because its vessels did not pass inspection this week, the Coast Guard said.

The company’s two vessels were ordered to cease operations on July 8 while investigators look into the cause of a flash fire that caused second-degree burns to an employee, Coast Guard officials said.

Coast Guard inspectors have been working with the owner this week, but did not issue a certificate of inspection, which would allow the vessels to carry passengers.

“We still have concerns about the engineering systems on board so we’re going to hold off on reissuing the certificate,” said Cmdr. Jason Neubauer, chief of prevention for Coast Guard Sector Honolulu. “We have to make sure the vessel satisfies our concerns.”

He said the Coast Guard told the company what it wants done, and it’s up to the company to contact the Coast Guard for a verification exam.

Hawaii Duck Tours has two “duck boats,” the distinctive yellow amphibious craft that can travel on both land and sea.