This story has been updated from a previous version.
A Northern Virginia office building that houses a clinic that performs abortions was evacuated twice Thursday after fireworks exploded inside an elevator and then a bomb threat was found.
Police gave the all-clear later in the day; no bomb was found.
Police have not said whether they believe the clinic, Falls Church Healthcare Center, was the target. A similar bomb threat against the building was made in July.
A clinic spokeswoman thanked police and described aggression against abortion providers.
"Pro-choice healthcare centers have experienced an increase in harassments, threats and the presence of protesters since the election," Katy Crigler said in a statement.
Police were first called to the building on the 900 block of S. Washington Street about 9 a.m. after someone heard a loud noise like an explosion and smelled smoke.
Fire investigators found exploded fireworks inside an elevator. No injuries were reported.
The all-clear was given at 9:30 a.m., and the building was reopened.
Then, two sheets of paper with the word "bomb" were found taped to the floor by a back entrance about 12:30 p.m.
The building was evacuated for a second time.
Bomb-sniffing dogs assessed the threat, and the all-clear was given for a second time about 2:45 p.m.
A few anti-abortion demonstrators stood with signs across from the clinic. They are not suspects.
The investigation is ongoing. Surveillance video footage from in and around the building will be key.
Anyone with information is asked to call Falls Church police at 703-248-5053.
Stay with News4 for more details on this developing story.