This story is happening in the city of Tijuana.
I work for a company that provides mental and behavioral health services, and most of our clients are children with autism.
The first strange thing happened when one morning my workmate and I were turning our computers and the A/C on. She was in the lunch room and I was in the main office when I heard her say, "yes, I'll be right there." She came to the main office and said that she clearly heard me calling her name, which I didn't, but we shook it off and blamed the neighbors. However, this started happening on a daily basis. Sometimes it was me who heard someone calling my name and we finally decided to pay a visit to our neighbors, only to discover that they open their office 30 minutes later than us but we didn't know this since we had just moved into the office we are now and we were not familiar with them.
That stopped for awhile, but then we were facing another kind of situation. Every morning that we came in, we found the fan of each office spinning at full capacity! There is no way someone could have got in during the night hours because only the two of us can set on/off on the alarm system and we always made sure not to leave equipment or any lights on. We checked the check-in/out control and we both confirmed that neither of us came in the night.
These days we are dealing with noises that come from the office where we work with our children. We've heard toys slamming on the wall, chairs being dragged around, toys activating themselves... But we've never seen anything. It's kind of scary, but we are getting used to it and every now and then we greet whatever is in here to see if they can lay it down a little and work at ease.