These are the two women who were caught on more than one occasion apparently casing the Dallas Love Field airport—and there were four “explosive devices” found in their home: Women arrested after police standoff.

Kimberly Al-Homsi called 911 about 12:40 a.m. Monday. She said her friend, Aisha Hamad, had threatened her with a knife. The two are noteworthy because a few months ago, they were seen at Dallas Love Field, both dressed in camouflage pants under traditional Muslim robes, conducting what appeared to be surveillance, officials said.

Police say that Monday morning, when an officer came to the door, Ms. Hamad threatened to shoot him. She told him the only way she would leave was in a body bag.

So began the standoff, during which she fired a paintball gun at a tactical robot and missed, police say, and at the end of which a negotiator persuaded her to come out peacefully. Once outside, Ms. Hamad, 50, fought with them while they tried to handcuff her, police say, so they used a Taser on her. Police took Ms. Hamad to a hospital, where she was to undergo a mental evaluation. She is likely to face assault charges, Arlington police spokeswoman Christy Gilfour said.

Meanwhile, police searched the home on Wembley Road and found four explosive devices, one of which was sitting on a bedroom table.

Citing an ongoing investigation, Arlington Assistant Fire Marshal Stephen Lea would not say what the devices were. “We do not know whether they would function as [explosive] devices until we have time to study them and look at them and test the materials,” Mr. Lea said. “I can tell you this; there wasn’t anything in there that would have blown her house to pieces.” …

The terrorism angle stems from Feb. 25, when the two women were spotted at Love Field acting in a way authorities found suspicious. Surveillance video showed one of them walking back and forth, apparently pacing off distances. When confronted, the women told officials they were looking for the Frontiers of Flight museum.

Two days later, the pair was spotted at the airport again. This time Ms. Al-Homsi, 42, was sitting on the hood of a car looking through binoculars at airplanes. Dallas officers stopped the car nearby, but the women refused to let police search it, authorities say.

The women also came under scrutiny after they were reported driving near the runways at Dallas/Fort Worth International Airport on July 4.