MILWAUKEE (CBS 58) — The U.S. State Department is urging U.S. citizens in parts of Mexico to shelter in place.

"When we landed, we were so surprised at all the chaos that happened during our flight, so we had no idea what we were walking into," said Rocio Becerril, immigration attorney.

On Sunday, the Mexican military, with the help of U.S. intelligence, took down one of Mexico's most notorious drug dealers. The leader of the Jalisco New Generation cartel, known as "El Mencho," was killed along with eight other cartel members.

Now, a wave of violence has washed over Puerto Vallarta.

"During our commute from Mexico City to Querétaro, it was about three hours. We didn't see anything. We did see heavy police, the national guard, local police, and police activity, which honestly made us feel safer," said Becerril.

Becerril landed in Mexico City from Chicago Sunday afternoon.

"It was a scary experience to be honest with you, because we were seeing all the videos of what was happening," said Becerril.

Milwaukee-based Destination Director Tanya Murphy is just south of Cancun, about 1,500 miles away from Puerto Vallarta.

"The distance between here and the things that are happening is the same as the distance as Minneapolis and Disney World, and you wouldn't say we aren't going to Disney World because of the protests that were happening in Minneapolis," Murphy explained.

While the rest of the country is currently safe, she says Puerto Vallarta is a tourist hot spot.

"We are in the middle of peak travel season for Mexico. There are probably a lot of people there now who are wondering when are they going to be able to go home," said Murphy.

The scene on the streets of the city shows plumes of smoke from torched cars and buses.

The U.S. State Department urged American nationals in parts of Mexico to seek shelter and remain in residences or hotels.

"They were pretty scared, pretty shocked, and unsure what their next steps were going to be," said Murphy.

Murphy has friends vacationing in that area.

"I do know that they were planning on coming home tomorrow, and they're not sure if they're going to be able to," said Murphy.

U.S. and Canadian airlines have halted flights going to the affected area.

Murphy says in Cancun, it's business as usual, so you don't need to change your plans -- but it's always a good idea to keep an eye on things just in case.