McEwen says it has initiated an investigation into the accident involving a contract haul truck driver killed when the vehicle overturned at the site.

"We are all deeply saddened by the tragic loss of life on our mine site," the company's chairman and founder, Rob McEwen said.

"Our immediate focus is to support his family, friends and colleagues at this most difficult time. Safety for everyone on our mine sites is our highest priority. An investigation is underway to determine how this happened."

McEwen Mining has lost one-fifth of its market value since the start of the year and recently reported a US$10 million loss for the first quarter of 2019 after operating problems at the key Black Fox mine in Timmins, Canada. The company also owns 49% of the San José gold-silver mine in Argentina, it is still heap leaching gold at Fenix in Mexico, and has Gold Bar advancing.

McEwen had to raise $25 million in March to increase its cash balance and had $50 million of debt at the end of that month. CFO Andrew Elinesky departed suddenly earlier this month.

The company's shares (NYSE/TSX: MUX) were up 4.5% Monday at US$1.50, capitalising the company at $540 million.