SAN DIEGO -- There's a new stage in Mexico's drug wars. The drug cartels are now acquiring the firepower of a Marine infantry squad.

A 10News I-Team investigation identified the guns of choice, and shows how they're smuggled into Mexico.

The recent carnage is proof of how much new firepower is in the hands of the Mexican drug cartels.

One recent rolling gun battle in Tijuana between two factions of the Arellano Felix cartel lasted more than three hours and left behind 19 bodies and an arsenal of firearms.

Even more frightening, most of the firearms came right through San Diego. Other than a couple of recent spot checks at the border, cars carrying guns have been able to sail easily south into Mexico.

“There are no searches. There's nobody stopping them on the other side,” said Shawn Hoben, Special-Agent-In-Charge of the San Diego office of the ATF.

Sources tell 10News the Mexican drug cartels have a list of "most-wanted” guns. In fact, all 60 guns recovered from the Tijuana bloodbath were on that "most-wanted" list.

The equivalent of the U.S. military’s M16, the semi-automatic AR15, is one of the guns on the list.

It can be purchased legally in some states in the U.S. and can easily be reconfigured into a machine gun in less than five minutes.

The AK47 is another weapon on the list.

A handgun called the “five-seven,” is dubbed "The Cop Killer" because its bullets go right through body armor.

“Its muzzle energy is unlike any handgun I've ever fired,” said 10News Anchor/Reporter, Kimberly Hunt.

“It’s a new generation of handgun with a power previously reserved for rifles.”

The other handguns on the “most-wanted” list are the 9mm, 38-Super and Colt-45.

And the drug cartels are also targeting a rifle that shoots the biggest bullet in the world, the Barrett 50-caliber.

It can take out a light armored truck from more than a mile away.

10News got exclusive access to the ATF vaults in San Diego that are full of weapons.

Hoben says he knows most were destined for Mexico.

“These drug trafficking organizations that are at war with each other, they want to have the best weapons they can get,” Hoben said.

57 of the 60 guns left on the streets of Tijuana were traced back to the U.S.

They were purchased in Washington, Nevada, Arizona, Texas and in California.

“The drugs go north. Guns and money so south,” said Hoben.

The guns go south using the cartel's drug routes.

Most are funneled through the San Ysidro border crossing and into Mexico.

“Yeah, they are warring. They're warring with the government down there. They're warring with each other,” said Hoben.

The war that rages south of the U.S. has, amazingly, not yet broken out in San Diego.

Many sources tell 10News that's no accident.

The cartels move their families to San Diego, so it's in their best interests to keep their turf wars south of the border.

To further the point that the cartels have ties to San Diego, there were 22 cars left on the streets of Tijuana after that deadly gun battle.

Eleven of them had California license plates.

A recent check of ATF gun seizures in San Diego shows, in the last two weeks, 70 guns, pipe bombs and thousands of rounds of ammunition have been confiscated here.

Among the weapons found were four machine guns.