Texas explosions: ‘Serial bomber’ hunted after tripwire sets off 4th blast

AUSTIN — Anxious Texans huddled inside their homes Monday as investigators scrambled for clues at the scene of another mysterious explosion here, the fourth in a string of attacks this month that authorities say are the work of a sophisticated “serial bomber” who has been terrorizing this city with increasingly complex devices.

The latest blast, which injured two men walking through a residential area Sunday night, marked an escalation in both the tactics and skills displayed by the bomber or bombers, police said. While the three previous bombs were hidden in packages delivered to people’s homes, the fourth device was left on the side of the road and was rigged with a tripwire, showing “a higher level of sophistication, a higher level of skill,” said Brian Manley, the interim Austin police chief.

“What we have seen now is a significant change from what appeared to be three very targeted attacks to what was, last night, an attack that would have hit a random victim that happened to walk by,” Manley said at a news briefing. “So we’ve definitely seen a change in the method.”