Updated: Package headed to Austin explodes in FedEx facility near San Antonio

Updated at 1:45 E.T.: A second device, which had not detonated, has been found at the FedEx facility in Schertz, Texas, according to officials.

A package headed to Austin exploded early Tuesday morning at a FedEx facility in Schertz, Texas, just north of San Antonio.

One FedEx employee suffered minor injuries during Tuesday's explosion, company spokesman Jim McCluskey said Tuesday in a statement.

It's the fifth explosion to rock the area in 19 days, and FBI officials are working to determine whether it's linked to four other blasts that have killed two and injured four others in Austin.

“We are investigating it as being possibly related to our open investigation,” FBI spokeswoman Michelle Lee told Reuters. “We can’t know for sure until we have an opportunity to look at the evidence itself.”

What happened?

A package filled with nails and metal shrapnel detonated while traveling on a conveyer belt at the FedEx facility at about 12:25 a.m. Tuesday, according to agents from the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives.

The package was sent from Austin and addressed to an Austin recipient, according to the Austin American-Statesman.

About 75 employees were working at the time of the explosion.

One employee was hurt and treated at the scene for non-life threatening injuries.

What's the timeline?

• March 2: A package bomb left on a doorstep killed 39-year-old Anthony Stephan House.

• March 12: Two package bombs exploded in separate locations, just hours apart. One killed Draylen Mason, 17, and left one woman injured. The other blast left a 75-year-old Hispanic woman seriously injured.

• March 18: A bomb activated by a trip wire injured two men in their 20s who were either riding or pushing their bicycles in a residential neighborhood.

• March 20: A second device, which had not detonated, has been found at the FedEx facility in Schertz, Texas, according to officials.

Which agencies are assisting?

Hundreds of FBI and ATF agents and forensic investigators are assisting with the investigation, KXAN-TV reported.

Also, about 100 Texas Department of Public Safety officers, as well as the Texas Rangers bomb squad, bomb-sniffing dogs and other agencies are involved.

Other local departments are sending bomb technicians and dog teams to assist.