In what experts call "Flash Flood Alley," the terrain reacts quickly to rainfall steep slopes, rocky ground, and narrow riverbeds leave little time for warning.

Ten teenagers were killed after being swept away by rising floodwaters from the Guadalupe River while evacuating their summer camp in July 1987, according to the National Weather Service. (Credit: NWS

The Associated Press has assembled an approximate timeline of the 48 hours before, during and after the deadly flash flood, beginning with the activation of the state’s emergency response resources on July 2 — the same day Texas signed off on the camp’s emergency plan for disasters.

The first weather emergency alert sent by the National Weather Service with urgent language instructing people to "seek higher ground now" was sent at 4:03 a.m. local time.

The downpours that swept away a children's summer camp and wreaked deadly havoc on huge areas of Texas caught holidaymakers by surprise. As the death toll passes 90 people, questions are being raised about whether adequate flood warnings were provided and why people weren't evacuated ahead of the deluge.

The psychological toll of recovering the bodies of flood victims in Texas is drawing increased attention as the death toll grows.

A massive Texas search and cleanup effort was set to enter its fifth day Tuesday in response to Guadalupe River flooding that surged through the area on July 4.

Rescuers searched the Guadalupe River for survivors of the Texas floods that killed more than 100 people over the July Fourth holiday weekend, with an unknown number of people still missing. The basin area was crowded with families and campers preparing to enjoy the holiday when pounding rain brought about catastrophic flash floods just before dawn Friday.