Does the 3-year term run from the accident or from when the victim learned of the damage?
It depends on the case: the general rule counts from the violation of the right (CC art. 189), but for many claims, especially insurance ones, STJ Súmula 278 requires counting from unmistakable awareness of the damage and its extent, which can come well after the event that caused the harm.
Can prescription be interrupted more than once?
No. CC art. 202 allows only one interruption per claim; a second interrupting event, if any, does not restart the term again. That differs from suspension under arts. 197 to 201, which can have several intervals added to the end of the term.
Does damage against the government also prescribe in 3 years?
No. Decree 20,910/1932 sets 5 years for claims against government entities, a longer term than the Civil Code's 3 years, and the Federal Supreme Court (RE 669.069, general repercussion) confirmed that this special term prevails over the Civil Code's general rule.