Really. First detected by a military satellite looking for Russian nuclear tests in space, gamma ray bursts occur somewhere in the universe about once a day. In an instant they release more energy than all the rest of those billions and billions of stars in the universe combined. That's equivalent to our sun's output for 1.3 trillion years or about 88 times the current age of the universe.
The bursts occur in all directions of the sky and last from a few milliseconds to a few hundred seconds. So far scientists do not know what causes them, but suspect the birth of a black hole.
Some very massive stars (at least 30 times more massive than the Sun) can collapse into black holes several million years after they form. The energy released in the formation of the black hole emerges out of the collapsed star in the form of a gamma ray burst—the "collapsar" model.