LONG ISLAND, N.Y. (NewsNation) — A three-day operation by U.S. Immigration and Customs Enforcement involved over a dozen individuals who have reentered the United States unlawfully — some of whom are connected to the MS-13 gang, according to authorities.

The operation, led by the Enforcement and Removal Operations team, targeted 15 individuals across Long Island who were wanted for several crimes, including homicide. These individuals were also in the U.S. illegally and were considered armed and dangerous.

NewsNation was able to ride along with the ERO team during this mission, getting a first-hand look at how the team operates. The officers who carried out the operation said the work they do is necessary to keep communities safe across the country.

On Thursday, 10 of the 15 wanted individuals were apprehended, and nine arrests were made. Four of those individuals had criminal warrants.

At least four of the people ICE targeted have affiliations with MS-13, which the Department of Justice describes as “a national and transnational gang composed largely of individuals of Salvadoran or Central American descent.”

Authorities said the people they sought were located in the Uniondale, Amityville, West Hempstead, St. James and Freeport areas of Long Island.

ERO officers with rifles locked and loaded surrounded and arrested Edwin Mendoza Melendez in Uniondale on Wednesday morning.

The team conducted early surveillance to know exactly what time Melendez, who is wanted for illegal entry into the U.S., twice as an aggravated felon, would be leaving his home.

A self-proclaimed member of MS-13, officers say Melendez has a tattoo of the gang on his stomach. He was recently arrested for possession of crack cocaine, which was what tipped off officers or federal officers to his whereabouts.

The gang has an estimated 10,000 members operating across 40 states.

“And they’re always seeking to recruit more individuals,” ICE ERO New York Field Office Director Ken Genalo said.

Leading the operation, Genalo is responsible for ERO operations in New York City’s five boroughs and nine counties outside the city.

“It shows that if they did it in their own country, they can do it while they’re illegally present in the United States,” Genalo said.

Here’s a look at some of the other people arrested so far this week:

• 11 have administrative warrants, meaning they missed required court dates or committed other minor crimes
• One man arrested this week is wanted by Interpol for murder in Honduras
• One man is wanted for attempted aggravated murder in El Salvador
• One man from Guatemala is wanted for conspiracy to commit murder
• One man was arrested for child rape
• One man, an alleged MS-13 member, was arrested for entering the U.S. twice illegally

Officials told NewsNation that many of the people they’re arresting this week gain entry through the southern border.

Some of the convicted felons the operation looked for were kicked out of the U.S. multiple times but had eventually sneaked back in through the southern border only to commit more violent crimes.

Earlier this week, 38-year-old Francisco Oropesa was arrested 20 miles outside Cleveland, Texas, where he’s accused of fatally shooting five people, including a 9-year-old child.

Oropesa, a Mexican national had been deported four times between 2009 and 2016, yet somehow he made it back into the country undetected and now he’s accused of committing multiple murders.

“This is all about securing the public safety, trying to rid society of these dangers they pose and that’s kind of what we’re here for,” Bryan F. with ICE said.

The ERO officers said there’s a misconception or false narrative that ICE is only interested in going after any immigrant who wants to live here peacefully. However, agents told NewsNation they’re really concentrated on going after dangerous criminals.

Devan Markham contributed to this report.