The Facebook posting was ominous.

On Monday, Gregory Twyman, 44, uploaded an image of a shotgun and a shotgun shell he bought at Walmart to his social media page, police said.

Yesterday, Twyman called 911.

"I need the police, I just shot my girlfriend," Twyman said, according to police.

When Chester County investigators arrived, they found Twyman sitting on his front porch in Coatesville, smoking a cigarette and still on the phone with 911.  They found Jamica Woods, his long-time girlfriend, inside. She had been killed by shotgun blasts to her torso, police said.

Twyman told investigators he had been fighting with Woods for days. He bought the shells at Walmart last week, he said.

Two days ago he posted an image of one of the shells on his Facebook page.

A friend immediately asked:

"What is that bro???"

"A shell fool," Twyman responded.

"I'm calling the ATF on your ass now… LOL…," the friend quipped.

"Gon be too late," Twyman wrote.

Another friend chimed in:

"CIA FBI ATF u know snitches be lurking amongst us on here… lol," she said.

Said Twyman, "Once I handle my business I don't give a f---!"

Police, who said Twyman has prior felony convictions, recovered a 12-gauge shotgun inside Twyman's Rokeby Road house.

Contact Sam Wood at 215 854 2796, @samwoodiii or samwood@phillynews.com