[Breaking news update, published at 6:55 a.m. ET]

SAN ANTONIO — An explosion occurred overnight inside a FedEx facility in Schertz, Texas, FBI San Antonio spokeswoman Michelle Lee said.

Based on preliminary information gathered at the scene, there could be a connection with the four recent Austin explosions, Lee said.

“We suspect it is related to our investigation,” Lee said.

No injuries have been reported in the explosion at FedEx, ATF spokeswoman Nicole Strong said. She said the ATF could not confirm that this explosion is associated with the Austin blasts.

The ATF’s Houston field division is at the FedEx facility in Schertz, the agency said on Twitter.

[Original story, published at 4:59 a.m. ET]

Police in Austin, aided by federal and state forces, are combing for clues to find the serial bomber behind four explosions.

But so far, there’s no word on any suspect or motive.

With the community alarmed and no clear answers, law enforcement is getting more manpower and resources to investigate the blasts that have killed two people and injured four others.

“There is an army of law enforcement folks on the scene right now. They’re getting all the resources they need,” Austin Mayor Steve Adler told CNN Monday. “This is a group that’s very determined and focused.”

For the fourth time this month, a device exploded in Austin Sunday night. But this time, instead of a package bomb left on residents’ doorsteps as had been the case in the first three explosions, a device was triggered by a tripwire, police said.

The two men who were injured in the latest blast are expected to recover.

Latest developments

• President Donald Trump has been briefed on the Austin bombings, a White House spokesman said Monday, adding that the White House pledges its support to local law enforcement.
• Three members of the Congressional Black Caucus called Monday for federal officials to classify the bombings as terrorist attacks and determine whether they are “ideologically or racially motivated.”
• The NAACP called the incidents “acts of domestic terrorism” and called for vigilance and caution for communities in Austin.

On the state level, about 100 Texas Department of Public Safety officers, sergeants, and special agents, as well as the Texas Ranger bomb squad, bomb-sniffing dogs, intelligence agents and helicopters are also involved, reported CNN affiliate KXAN.

Police departments in Houston and San Antonio are sending bomb technicians and canine teams to Austin, their police chiefs said Monday.

How are they examining the evidence?
ATF has taken evidence from the four blast sites, Austin Police Chief Brian Manley said.

“The prior three scenes are already in the lab at Quantico, and the evidence from the scene from last night is on its way to Quantico as well,” he told CNN’s Anderson Cooper Monday night.

“They’re looking at the devices, they’re comparing them, looking for similarities,” he said.

“The similarities they’ve seen to this point, lead them to believe — as we do — that these are all being constructed by the same person or persons who are responsible for this.”

How are they handling the tips?
Austin police has received lots of tips, Manley said Monday night.

“As each tip comes in, it gets assigned to either a team of FBI agents, ATF agents or Austin Police detectives to do follow-up work on,” he said.

Manley also urged residents to call police with any tips they may have.

“No matter how inconsequential you think it may be, that may be the piece of evidence we need to link it together and solve this, before we have someone else in our community that gets seriously injured or killed,” he said.

What resources are they getting?
Texas Gov. Greg Abbott announced more than $265,500 in emergency funding for the Austin Police Department and the Texas Ranger Response Team to purchase seven portable X-ray systems.

The systems can be used at the scene so they can quickly assess the safety of packages.

“I want to ensure everyone in the Austin region and the entire state that Texas is committed to providing every resource necessary to make sure these crimes are solved as quickly as possible,” Abbott said in a statement.

The reward for information leading to the arrest of anyone responsible for the blasts is at a total of $115,000.

What are police asking residents to do?
Police are appealing to residents to pay attention to their surroundings to see if something looks out of place.

Manley told residents not to touch or go near anything that looks suspicious.

“We now need the community to have an extra level of vigilance and pay attention to any suspicious device — whether it be a package or a bag, a backpack — anything that looks out of place,” Manley said Monday. “Do not approach items like that.”

Authorities are also asking anyone in the neighborhood with security camera footage to call police.

[van id=”tv/2018/03/19/exp-tsr-todd-austin-bombing-investigation.cnn”]
Many minority residents in Austin have been on edge since the bombings started, as the first three bombings killed or wounded minorities who received packages at their doors. Police have not discovered a motive, but have not ruled out the possibility those bombings could be hate crimes.

The fourth explosion injured two white males, who were injured by a device left on the side of a road and triggered by a tripwire.

“The use of a tripwire is far less discriminating than leaving parcel bombs at residences and suggests that the latest victims were not specifically targeted,” the global think tank Stratfor Threat Lens said.

The use of a tripwire suggests that the bomb maker is perhaps more sophisticated and capable of making a more complex bomb, law enforcement and analysts have said.

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