The U.S. Food and Drug Administration on Monday notified healthcare providers that it had received reports of five more deaths in patients using liquid-filled intragastric balloon systems to treat obesity, bringing the total death toll to 12 since 2016.

The balloon systems associated with the reports are made by ReShape Lifesciences and Apollo Endosurgery, the FDA said.

Shares of Apollo Endosurgery and ReShape were both down about 10 percent in late-afternoon trade.

The FDA said that it was working with the device manufacturers to better understand the issues, and had approved labeling changes last week to reflect information about possible deaths associated with the devices.

Apollo said four deaths had occurred in patients who received the company's Orbera Intragastric Balloon device since August 2017, when the regulator issued a letter warning healthcare providers of seven patient deaths.

ReShape said there has been one reported death of a patient implanted with a ReShape Balloon since the FDA issued the letter last year.

ReShape said it has not received any product liability-related claims in connection with the death.