Lindsay Lohan and her assistant Gavin Doyle were questioned by police today regarding the apparent robbery of a Hollywood Hills home where they both spent the night Sunday evening, a source tells X17online.com exclusively.

Lindsay stayed at a friend's home where she's attended several parties in the past, and woke up this morning to find the place had been robbed. No word yet on what was taken or how police believe the culprit entered the property, but the owner of the home had all his guests on lock down this afternoon until police could question everyone.

We're told the whole thing's still a mystery and no suspect has yet been identified. Stay tuned for more info ...