A couple from Garden Grove, California who was visiting Tijuana, a Mexican border city, didn’t return home as expected, prompting their family and Garden Grove Police Department to look for them frantically.

Jesus Guillen, 70 and Maria Lopez, 68, headed for Tijuana Friday morning in their truck to collect rent from their tenants. They were likely to return Friday itself but they didn’t, Kron 4 reported, citing police.

Their children have been searching for them since. Their worried daughter initially used the “Find My Phone” app service to track them down. The app indicated they were still present at their Tijuana property although a relative had earlier told her that they left. The FBI, U.S. State Department, and Mexican authorities have been notified about their disappearance. The daughter thereafter reached Mexico to post flyers and assist police in the search operation.

A neighbor of the couple, Danielle Razi recalled them as a “tight-knit family” who lived there for decades. "They're the best neighbors we've ever had and probably one of the only original neighbors from my almost 40 years living here," Razi told ABC 7.

"She's got a few great kids with lots of grandkids and they're always here ...every holiday," Razi added, referring to Maria. "We've all grown up with them. It's heart-wrenching to think about."

In this photo a teenager volunteers and hands out flyers for a missing boy. Getty Images