"We are clearly dealing with what we expect to be a serial bomber at this point," Manley told reporters. "Based on the preliminary review that we have done at this time, we have seen similarities in the device that exploded here last night and the other three devices that have exploded within Austin starting on March 2."
Manley said he does not think a motive will be clear until the person or people responsible are found.
The three other explosions were all package bombs delivered to homes in the city. Two people were killed and at least two others were injured after by those devices.
Local and federal authorities, including the governor of Texas, have offered a $115,000 reward for information leading to a conviction of the bomber.