From the Daily Star (can't post full URL)
/news/world-news/650933/Hong-Kong-airport-fire-American-Airlines-plane-cargo
The spokesman said: "An external piece of loading equipment had a mechanical issue and caught fire while preparing to put cargo in the hold of American Airlines flight 192 from Hong Kong (HKG) to Los Angeles (LAX).
"As a result, a pallet on the loading equipment containing non-hazardous goods also caught fire."
Perhaps not Li-ion batteries after all.