Four thugs — one posing as flower deliveryman — tried to rob a Long Island home but their attempt was thwarted by a quick-thinking teen who locked herself in the bathroom and called 911, cops said yesterday.

The fiends, two of whom were armed, busted into the house in Woodbury at around 1:20 p.m. Friday, ordered a 26-year-old woman to lie on the ground and then tied up a 61-year-old woman and tried to grab her cash and jewelry, cops said.

But an 18-year-old girl had hidden from the intruders and alerted authorities.

The four men, from Brooklyn and Queens, fled but were later captured.

No one was hurt.