WASHINGTON - A monster black hole shredded a Sun-like star, producing a strangely long-lasting flash of gamma rays that probably won’t be seen again in a million years, astronomers reported Thursday.

That is definitely not the norm for gamma ray bursts, energetic blasts that typically flare up and end in a matter of seconds or milliseconds, often the sign of the death throes of a collapsing star.

“This is truly different from any explosive event we have seen before,” said Joshua Bloom of the University of California-Berkeley, a co-author of research on the blast published in the journal Science.

Initially spied on March 28 by NASA’s Swift spacecraft, which is trolling the universe for gamma ray bursts, this particular flash has lasted more than two months and is still going on, Bloom said in a telephone interview.