OURAY, Colo. — Authorities are trying to determine exactly what sort of accident occurred in a mine in southwestern Colorado that left two miners dead of carbon monoxide poisoning and injured 20 others.

The Ouray County sheriff's office was called to the Revenue-Virginius mine at 7:20 a.m. Sunday, Ouray County spokesman Marti Whitmore said.

The miners were underground and were confirmed dead Sunday.

Authorities said at a late night news conference that the two died from carbon monoxide poisoning. But the source of the gas was under investigation.

Investigators are looking at whether a blast on Saturday played a role.

The 20 injured were taken to area hospitals, and all but two were treated and released, Whitmore said. There was no word on the conditions of the two hospitalized workers.

NEW YORK — Walmart said about 10 of more than six dozen Bangladesh garment factories failed safety checks in audits it commissioned.The retailer hired Bureau Veritas to check some 200 factories it uses in Bangladesh after the April collapse of the Rana Plaza building killed more than 1,100 people and highlighted often grim conditions in the country's garment industry.About 75 factories have been audited so far and Walmart said it will release results for other factories as the inspections are completed.It said factories that failed audits have since made improvements.In the aftermath of the disaster, major European clothing retailers signed up to a system of factory inspections in conjunction with labor and activist groups.