There was a fourth explosion in Austin on Sunday night—hours after police urged the person behind three package bombs earlier this month to contact them and explain their "message." Officials say two men in their 20s were seriously injured in the blast in the southwest of the city, miles away from where the earlier bombs killed two men from prominent black families and seriously injured an elderly Hispanic woman, the Austin American-Statesman reports. "We're not going to take questions because we simply just don’t know anything at this time," Interim Police Chief Brian Manley told reporters, promising there would be a briefing in the morning. Mayor Steve Adler said he would ensure police had all the resources they needed to investigate.
At a news conference hours before the latest explosion, Manley said the motive or ideology behind the package bombs was unknown and addressed the bomber or bombers, the New York Times reports. "These events in Austin have garnered worldwide attention, and we assure you that we are listening," the chief said. "We want to understand what brought you to this point, and we want to listen to you." Investigators say they believe the same person built the devices used in the first three blasts, one on March 2 and two on March 12. Investigators, who say they are looking for possible links to other package bombings around the country, have received more than 700 tips about suspicious packages over the last week, Reuters reports. Police are offering a $115,000 reward for information.