It's now believed whoever made a mail bomb that exploded at a policeman's home is likely behind a similar bomb mailed to another home.

ALAMEDA (KPIX) — A home-made explosive slipped past the United States Postal Service and was hand-delivered to a Bay Area police officer’s front door. His wife was the one who discovered the bomb and was hurt when it went off.

KPIX 5 has learned whoever made this explosive is likely responsible for a similar bomb that was mailed to a home in East Palo Alto, in October.

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“Since Ted Kazinsky and the Unabomber the postal service, inspectors and the FBI, they work diligently to try to prevent these things from happening,” says Jeff Harp, KPIX 5’s Security Analyst.

But somehow the mail bomb package got through the system twice in the past 2 months.

On Friday, it was to a police officer’s home on Bay Farm Island in Alameda.

Inspector Jeff Fitch with the Postal Service says the mail bomb is very serious and being investigated by a number of law enforcement agencies including the Bureau of Alcohol, Tobacco, Firearms and Explosives.

“If anybody spots anything, we’re asking people to call 911 or call postal inspectors,” he said.

The package was delivered by the USPS to the police officer’s home on Bay Farm Island in Alameda. He was off duty at the time.

Sources said the officer’s wife opened the package she thought it looked suspicious so she threw it. When the bomb exploded she suffered minor burns and ear trauma from the blast.

The package was 11 inches long, too big for a mailbox. That is why it had to be hand delivered.

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“Some of these parts are very rudimentary,” said Harp. “They just are wires that when you open a package, they pull on each other and they make contact, and that’s what completes the circuit. Some of them are not very sophisticated but there’s always some sort of footprint left of how this device was made.”

Now investigators believe this bomb was created by the same person who mailed another bomb to a home in East Palo Alto on October 19. A father was injured when he opened it. The package was sent to his son. The two share the same name.

“It’s very serious, it’s a serious federal offense,” said Fitch. “We’ve got a whole task force of people working on it.”

Investigators are working now on trying to reconstruct the package so that the mailing label and serial number can be read. That information will point them to the exact post office the package was dropped off at.

Surveillance video will be examined since all post offices have cameras recording people who mail packages.

KPIX 5 talked to a mail carrier in Alameda who said carriers have been trained on how to spot suspicious packages.

“I have a book of rules that I follow to the best of my ability, and try to stay safe.”

With so many packages being delivered over the holidays, inspectors warn people that if they receive a package they weren’t expecting, or looks suspicious, do not open it. Contact police immediately.

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As for the reason the police officer was targeted, at this point, investigators do not know.