Colonia Obrera, Tijuana: Third-World conditions just 15 minutes south of the U.S. border. Shanty-type homes dot the hillsides. Many are built with tires, discarded oil barrels, even Styrofoam.
"There's toxic gas and sometimes the gas flares up and becomes a fire. Two years ago we had 18 homes burn down," said missionary pastor Carlos Montoya.
It's here that nearly 100 volunteers, including doctors, nurses, dentists and medical students, have come to provide free medical care.
The process begins in a makeshift reception area. The patients get registered, then stand in line for services. Some of them will see the dentist, some of them will get their blood pressure checked, others will visit this clothing donation site.
By the time the day is through, doctors will have seen more than 500 patients.
Dr. John Rodarte of Pasadena leads this group of volunteers known as Healing Hearts Across Borders.
"I've grown to love the people here, because I've been here almost a decade," said Rodarte. "I've seen some of these people grow up from kids to adults now having their own families."
Maribel, 10, had a life-threatening heart condition when her parents brought her to the Healing Hearts clinic five years ago.
"At that point, she couldn't even walk to the clinic," said Rodarte. "So she couldn't go to school, couldn't play with the other kids at all. She literally did not have long to live."
Maribel had life-saving surgery at Mattel Childrens Hospital UCLA, where she now returns for yearly check-ups.
Julio is another success story. He also had surgery at UCLA to repair a congenital heart defect.
"He said that he thinks this is very important because doctors come here and they help take care of people, give them medicine and make him them better," said Rodarte.
But most of the nearly 1,000 patients Healing Hearts sees over two days have conditions like diabetes that can be managed with proper care and medication.
A lot of medication were donated.
"There's a lot of chronic conditions like diabetes and hypertension that are pretty cheap and pretty easy to treat... and if it wasn't for this clinic, these patients wouldn't see any treatment at all," said USC medical student Ian McQueen.
There's Mariachi music and free music lessons with volunteers from the Mariachi Conservatory in Boyle Heights.
"I think it makes a big difference in our lives and it just makes us appreciate what we have at home with our own daughters," said Esperanza Juarez, The Mariachi Conservatory.
Face-painting and games help children help pass the time. There's donated clothing and shoes. Volunteer medical students fill bags of food for families to take home.
"We started off originally with a small SUV coming down, working out of the back of a truck," said Dr. Kevin Lake.
It's grown much larger on this trip as nearly 100 volunteers gave their time over two days.
"It's become part of what I do. It's rewarding and sometimes I think they give me more than I give them," said Dr. Marya Miyamoto, L.A. County Juvenile Hall.
"Oh, I love doing it. I love working with all the people," said Dr. Lloyd Turner, a dentist.
For Dr. Marco Monares, it's personal.
"You know, my parents are immigrants themselves and I have a close connection, a close bond," said Monares. "And you know, I was uninsured as a child and sometimes didn't receive the best treatment or even a kind face, so that's why I do it, to give back."
Healing Hearts Across Borders is working to raise money to build a permanent medical clinic at Colonia Obrera.
If you'd like to help, or get more information, log on to http://www.healingheartsacrossborders.com/