Some elements in particular are of note
"The men also were carefully buried Christian-style, lying on their backs with arms crossed over their chests, though many appear to have been wrapped up in large maguey cactus leaves, rather than placed in European coffins.
The mass grave contained evidence of an Aztec-like ritual in which offerings such as incense and animals were set alight in an incense burner, but Spanish elements including buttons and a bit of glass also were present."
This mix of goods and especially practices suggests a number of possibilities, though speculating further based on the limited information here is not the best course of action.
Update: More details (in Spanish)