Villarreal's game at home to Celta Vigo was briefly suspended on Saturday night with just three minutes remaining after a smoke bomb, reportedly containing tear gas, was thrown from the crowd.
The visitors were leading 1-0 thanks to Fabian Orellana's goal in the 83rd minute when the object was thrown from the Villarreal section of the crowd and landed in the Celta penalty area.
None of the players were struck, but referee David Fernandez Borbalan quickly suspended the game after fans sitting near where the smoke bomb had landed rushed to the exits covering their mouths and noses.
Numerous Spanish media outlets reported the offending object was a tear gas canister.
However, after the smoke had subsided, both sides returned to the field and a fine free-kick from Nolito sealed a 2-0 win for Celta.
It is the second time this week that a match in Spain has been blighted by an object thrown from the crowd as Atletico Madrid were fined 600 euros ($820) after Real Madrid's Cristiano Ronaldo was struck on the head by a lighter during their Copa del Rey match on Tuesday.