How to spot a bottle bomb

AGAWAM, Mass. (WWLP) - Checking the mail with caution.

There was more than just letters in several Agawam mail boxes this week.

Someone placed soda bottle bombs inside, at least two exploded.

Paul Broz of Agawam said, “My dad goes to the mailbox and I don't want anything happening to him. ”

The explosives look like bottles that are a bit swollen that have little soda left inside.

If you see anything that looks like that, don't touch it, back away and call 911.

John Hauser of Agawam said, “My biggest concern is like I said is this something that explodes when you open the mailbox or is it a bottle lying in and if you shake it then it blows. ”

The bombs are made by combining chemicals in a sealed up bottle.

It builds up pressure and eventually bursts.

How easily they detonate depends on how much pressure has built up.

Broz said, "They're bombs yea and in this world and in this day and age it's not a good thing. ”

They can easily cause a lot of harm.

First and second degree burns and eye injuries being the most common.

"I think it's just a couple of kids that don't know what they're doing and when they get caught they will know what they are doing," said Hauser.

Police have made one and more arrests may follow.