A car is submerged on a freeway flooded by Tropical Storm Harvey on Aug. 27 in Houston. (Charlie Riedel/AP)

It was a dark and scary night in Houston and its suburbs.

As heavy rains continued to inundate streets flooded by Hurricane Harvey, residents stranded in their homes vented their fear and anxiety and pleaded for rescue on social media.

“Urgent please send help,” a woman wrote on Facebook early Monday morning. “My parents are in a 1 story home and the cypress creek is rushing in their home. PLEASE.”

Water levels for the creek near Interstate 45 will possibly top the levee by Monday morning, according to the National Weather Service.

“please help us at 9321 Oak knoll lane,” a resident tweeted late Sunday. ‘we have been flooded in over 8 hours please help us no one has came the water is rising …”

Emergency phone lines, the woman wrote on Facebook, were all busy.

“I have a friend on his roof in Greensbook Place,” tweeted another man. “how can they get rescued at this hour?”

As the rain continued to fall and water levels from the storm continued to rise on late Sunday night and early Monday, residents expressed desperation and frustration, complaining on social media about busy phone lines and unanswered calls from emergency services.

Houston Police Chief Art Acevedo, who live-streamed as he drove on empty streets late Sunday night, said “crazy heavy” rain was making it difficult for emergency services to rescue those stranded.

“It’s hard to see,” Acevedo said, as he drove on empty roads. “Flooding is still happening all over the place. Luckily, people finally got the message to get out of here. Sadly, it is making our rescue operations very difficult. So people that are still stuck in homes that are flooded, it is extremely difficult to get to you.”

Just after 9 p.m., a woman in North Houston reportedly went into labor. A family with five children, an elderly man with a broken hip and a mother running out of formula for her three-month old baby were among those in the country’s fourth-largest city waiting for rescue long after the sun set, according to messages in a Facebook group for victims of the flooding.

Authorities overwhelmed by the sheer number of calls for help said Sunday that emergency services were at capacity and residents should only call 911 if their home was in “imminent danger.”

From 10 p.m. Saturday through 1 p.m. Sunday, Houston 911 received over 56,000 calls, according to local authorities. During an average day, they usually handle about 8,000.

The rain totals over the past two days in some areas — up to 33 inches and getting worse — were creeping close to Houston’s average annual rainfall of 49 to 50 inches.

The U.S. Coast Guard tweeted Sunday evening that emergencies should be called into authorities, not reported on social media sites.

But many Houston residents nonetheless turned to Facebook, where a group connecting victims of the flooding with volunteer rescuers had thousands of posts and more than 100,000 members by early Monday.

“It’s getting harder day by day,” a man said in a Facebook live from outside his Houston apartment around 2 a.m. “It’s not looking good,” he said as the wind and rain began to pick up after a lull.

“I can’t sleep. I’m thinking about what I’ve got to do,” he said as he looked into the camera. “If I’ve got to swim I’ve got to swim. If I’ve got to run, I’ve got to run.”

On Facebook, commenters offered prayers and warnings, telling him to be safe.

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