A pedestrial walks April 30 on the Northwest Branch trail in Hyattsville, Md. A half-dozen women and girls have been raped on the trail so far this year. Police think they may be seeking two suspects. (Bill O'Leary/WASHINGTON POST)

The ominous signs are tacked on both sides of the opening in the black chain-link fence, warning travelers who venture out of the West Hyattsville Metro station that a rapist — or rapists — has been terrorizing the trails that lie ahead.

One woman was headed to work when a man forced her into the parking lot of an abandoned warehouse. Another was going to visit a friend when a man put a knife to her throat and threw her into the bushes. A 14-year-old girl was on her way home when a man ordered her into the woods at gunpoint.

Since late January, police say, six females have been attacked — four of them raped — as they walked along the Northwest Branch Hiker/Biker Trail, or in the apartment complexes, parks and neighborhoods that it connects. The string of incidents, the most recent on April 20, has sparked fear and anger among those who use the sprawling network of pathways and bridges as a route home from work or a shortcut to the Metro.

“When I’m coming at night, I don’t walk here,” said 44-year-old Donna Barnes, a housekeeper who was on the trail on a recent afternoon, heading to the grocery store. “I’m so scared.”

In each case, police said, the victim has described the assailant as a Hispanic man in his 20s or 30s, standing between 5-foot-5 and 5-foot-8 and weighing about 150 to 190 pounds. But there are enough differences in the victims’ accounts to make investigators think they might be hunting more than one person, police said.

In three cases, police said, the attacker used a knife; in two cases, he used a gun. In two cases, police said, the attacker robbed his victims. Four attacks occurred at night, one was around 5 p.m., and one happened at noon.

And though composite sketches from two of the cases are similar, a sketch in a third case seems distinctive, police said.

“There are more indications that there is more than one person than there is a single person,” said Capt. Stanley Johnson, a spokesman for the Maryland National-Capital Park Police. “There’s nothing that links any of them together right now.”

The attacks have occurred in three separate police jurisdictions, and along with the Park Police and Mount Rainier and Hyattsville police, Metro Transit and Prince George’s County investigators are helping look into the case and providing the trail area with extra attention.

Warning signs displaying composite sketches of the attacker in each case are posted on trees, lights and trash cans that line the Northwest Branch trail’s wooded pathways, which connect several garden-style apartment complexes in northern Prince George’s County with the Metro station and some neighborhood parks.

Police said they have beefed up patrols of the trails, even sending in a female undercover officer as bait. No one approached her for several nights, and investigators are still trying to find the man — or men — responsible.

“Of late, there’s more cops than customers on that trail,” said Mount Rainier Police Chief Michael Scott. “We got to find this guy, so hopefully he’ll slip up without hurting anybody.”

On a recent, overcast afternoon, only a few people were biking or walking on the trails. Some casually sang along with music playing through headphones. Others walked more hurriedly, glancing over their shoulders.

Emmanuel Anderson, 27, a Howard University student who uses the trails regularly, said that since the attacks began he has asked his girlfriend to talk to him on the phone while she is walking the trails alone. He said he also worries for his own safety and has started taking a cab home at night.

“When I first started walking, it was actually the deer that gave me the heebie-jeebies,” Anderson said. “I just hope that they eventually find the person.”

Police think the first attack came about 2:40 a.m. Jan. 28., when a 19-year-old woman walking from the Metro station was raped in the bushes at a Buchanan Street apartment complex, where she had gone to visit a friend.

There was another attack in February, three in March and one in April. Three cases occurred on the network of trails. Two were reported in the Mount Rainier apartment complex and one on a Hyattsville road near the Metro station, police said.

Hyattsville Police Chief Douglas Holland said the description of the attacker in his department’s case — which occurred Feb. 23 in the woods off the 2700 block of Jamestown Road — was similar to that in the attacks on the trail, but investigators could not conclusively link the cases. Scott, too, said that he did not know definitively whether the two attacks at a Mount Rainier apartment complex were connected to the others but that “the descriptions are vaguely the same.”

Johnson, the Park Police spokesman, said that the three attacks on the trail did not appear to be connected to the attacks off it and that the most recent trail attack, on April 20, seemed to be distinct from the first two.

In that incident, Johnson said, a 14-year-old girl was walking near Kirkwood Neighborhood Park, toward Chillum Community Park, when a man with a gun approached her about 5 p.m. The man forced the girl into the woods, then raped and robbed her, Johnson said.

Johnson said the girl described her attacker as having hazel eyes — “pretty distinctive,” he said, from other victims’ descriptions.

While some on the trail said the attacks have sparked fear, others said they are doing little more than trying to be aware of their surroundings.

A 44-year-old laundromat attendant — who, to protect her privacy, declined to give her name — said she would continue to use the path as a shortcut from her home to the pharmacy. She said she had been raised with four brothers and knew how to defend herself.

“If he attack me, I’m not running,” the woman said. “I’m gonna kill him.”