Bumbo International Trust is voluntarily recalling more than 4 million Bumbo Baby Seats sold in the United States and Canada after scores of injuries were reported, including skull fractures, the company and U.S. and Canadian authorities said on Wednesdayy.

Consumers should stop using the product until they install a free repair kit, which includes a restraint belt and a new warning sticker, and never use the Bumbo seat on an elevated surface, the South Africa-based company, as well as the U.S. Consumer Product Safety Commission (CPSC) and Health Canada, said in statements.

The recall involves about 4 million Bumbo seats in the United States and about 340,000 in Canada.

Since 2007, at least 50 U.S. incidents have been reported in which babies fell while the molded-foam seat was on a raised surface. Nineteen of the incidents included skull fractures, the company and the CPSC said.

Another 34 reports have been received of infants hurt while the one-piece seat was on a floor or an unknown elevation. Two babies suffered fractured skulls.

Five incidents have been reported in Canada, with three minor injuries, Health Canada said.

About 1 million Bumbo molded-foam seats were recalled in October 2007 in order to provide more warnings against use on raised surfaces.

The U.S. and Canadian moves come after consumer groups urged the CPSC in February to recall the seats, said Rachel Weintraub, director of product safety at the Consumer Federation of America, one of the advocacy groups.

The Bumbo seat has several warning labels on the back. Seats made since 2008 have another label on the front warning against use on raised surfaces.

The seats were made in South Africa and sold at Babies R Us, Sears (SHLD) Target Corp (TGT), Toys R Us, USA Babies, Walmart (WMT) and other stores and online sellers. They were sold from August 2003 through August 2012 for between $30 and $50.