UPDATE: The suspected Austin bomber is dead following an officer-involved shooting on Interstate 35, three law enforcement sources confirm to KXAN's Sally Hernandez. 

The shooting happened on Interstate 35 in Round Rock near Old Settlers Boulevard around 2 a.m. Wednesday. 

Round Rock police say while northbound I-35 is open, southbound I-35 will be closed for the next four to six hours -- up to 9 a.m. -- due to the investigation.

A law enforcement source says the suspected bomber blew up a device inside a vehicle. Police activity has centered in the parking lot of a Red Roof Inn at 1990 N. I-35, just south of Chisholm Parkway.

Michael Luna, a witness staying at the hotel who is ex-military, tells KXAN the blast sounded like two grenades going off. 

RRPD says there is no immediate danger to the public. 

A multi-agency investigation that spanned numerous locations and two cities over the span of several weeks led authorities to the suspect in Round Rock.

For the latest details go to KXAN's website.

PREVIOUS STORY: ROUND ROCK, Texas (AP) — Police in Texas say they are working an officer-involved shooting but it is unclear if it’s related to the recent spate of bombings.

The Austin Police Department tweeted early Wednesday morning that the shooting happened in the 1700 block of N. Interstate 35.

There have been multiple reports of heavy police activity in the area.

Investigators have been pursuing a suspected serial bomber in Austin since the first explosion on March 2. A 39-year old man was killed. A 17-year-old boy was killed and two women were injured in two separate blasts on March 12.

On Sunday, two men — ages 22 and 23 — were injured in a blast triggered by a tripwire. A worker at a FedEx distribution center was treated and released Tuesday morning after reporting ringing in her ears.

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