Residents of Port Arthur posted urgent pleas for rescue on social media Wednesday as the Texas city struggled to function after days of hammering rains from Tropical Storm Harvey that forced closure of the nation's largest oil refinery there.

The city was slammed by more than two feet of rain over a 24-hour period, flooding the civic center that had been serving as a shelter for more than 100 flood victims. A community center then was set up for evacuees.

"Our whole city is underwater right now but we are coming!" Mayor Derrick Freeman said in a Facebook post. "If you called, we are coming. Please get to higher ground if you can, but please try stay out of attics."

Water flowed like rivers in streets, and rescue efforts were further slowed by an apartment fire that forced first-responders to evacuate residents of the complex. Lightning also delayed some rescue efforts, Freeman said.

"My best friend and her family are stuck," tweeted one woman; another tweeted that her grandfather needed a rescue. Both tweets included addresses for emergency personnel or volunteers with boats.

Harvey, which slammed into the Texas coast Friday night as a full-blown hurricane, has lingered in the area since. The storm made landfall a second time early Wednesday in Louisiana, about 50 miles east of Port Arthur.

The Saudi-owned Motiva refinery in Port Arthur began "a controlled shutdown" at 5 a.m. Wednesday because of the storm.

"Return to service is contingent upon recession of floodwaters in the area," Motiva said in a statement. "Our priority remains the safety of our employees and the community."