SAN ANTONIO – Mark today as one of the greatest mysteries of summer 2019.

Just after 1 p.m. Wednesday, KSAT.com began receiving reports from viewers who said they heard an explosion in South Texas.

From La Vernia to more than 70 miles south in Beeville, viewers said their homes or businesses began to shake after hearing a "loud thunder."

@ksatnews in Karnes county a loud noise was made and the ground shook. Any word on what it was. Felt and heard in Pawnee to Runge and south of Kenedy up to the LaVernia area????? — RG (@the1xrayman) July 10, 2019

Am i the only one that heard that huge explosion in kc?!😅 — madison paige :) (@clubb_madison) July 10, 2019

"In Karnes County, a loud noise was made and the ground shook. Any word on what it was," a viewer asked KSAT.com.

"Was there another quake in Karnes County? Particularly Kenedy? Just heard a loud thunder about 10 minutes ago," another viewer said.

In response to numerous calls and messages, KSAT.com contacted law enforcement agencies in Karnes and Wilson counties.

The La Vernia and Kenedy police departments informed KSAT.com they had not received any reports of an incident and that no emergency vehicles have been dispatched to any scene.

In February 2015, residents near the San Antonio International Airport made similar reports of hearing an unusual, jarring noise that caused their homes to shake.

Because airport officials believed the noise was due to military activity in the area at that time, KSAT.com contacted officials with Joint Base San Antonio-Randolph, which is not too far from La Vernia.

JBSA-Randolph officials told KSAT.com their pilots do not fly "supersonic" and were not the cause of the apparent explosion many felt in the area.

So, we are left with the question: What was it?

If you felt the explosion and want to leave your account, share your experience in the comment section below.