[A Glock was found at Sandy Hook Elementary School in Connecticut following the killing of 20 children and 8 adults:]

A common element links many of America's recent mass shootings: the presence of semiautomatic weapons in the arsenal of the shooters.

After a deadly rampage at a Colorado movie theater, an attack on an Arizona lawmaker and others, the mowing-down of Sikhs at a Wisconsin temple and the mass killings at Virginia Tech, law enforcement found at least one semiautomatic pistol in the possession of the killers.

And, on Friday, authorities said they seized two such weapons at the scene of the horrific slaughter at Sandy Hook Elementary School in Newtown, Conn., where 20 small children and six adults died.

In all but one of those tragedies -- and in other earlier ones, including a mass shooting in Connecticut 15 years ago -- Glock semiautomatic pistols played a role.

The high-power capabilities of Glock pistols, as well as the ease of concealing them, attracts those bent on a high body count, according to criminal-justice experts. They are legally sold in gun shops and online, some for less than $500.

[A Sig Sauer was also found:]

...the weapons of choice for elite units around the world..., and the smart choice for anyone? A hard-earned reputation for getting everything right – design, materials, precision manufacturing, ergonomics, function, safety, accuracy, reliability, durability, maintenance, accessories and options.

...the pistol to reckon with. 

[The Sig Sauer was also the favorite of a certain Philadelphia gang a few years ago:]

These gangsters loved a semiautomatic pistol called a Sig Sauer. Most gang members had them. And they hung onto the $500 guns murder after murder.

[And a Bushmaster .223 rifle was found in the trunk of the Connecticut shooter's car:]

The Bushmaster was also used in the 2003 Washington, D.C. sniper shootings where 10 people were killed and two people arrested.

That incident resulted in a lawsuit settlement and eventually Bushmaster's Windham, Maine facility closed in 2010, but owner Dick Dyke started a new rifle manufacturing company called Windham Weaponry Inc. soon afterward.

Bushmaster's parts and gear are still available online.