Police trying to establish contact with the Washington-area sniper said Monday that a phone call had come in but was too muddled for authorities to understand. They pleaded with the person to call back.

"The person you called could not hear everything you said. The audio was unclear and we want to get it right. Call us back so that we can clearly understand," Montgomery County, Md., Police Chief Charles Moose said.

Moose said he could not discuss the message further.

Moose made no mention of a development in Richmond earlier Monday in which police seized two men for questioning in the attacks.

Hanover County Sheriff Stuart Cook said the men were taken into custody about 8:35 a.m. at or near an Exxon station in suburban Richmond.

"The two people we have in custody are being questioned as regards the sniper shootings," Cook said. "When we have further information that we can give to the public ... that we've concluded this case we'll do so, but that's not the case at hand."

He refused to describe the men as suspects in the string of shootings that have left nine people dead and three wounded.

During an earlier news conference, Moose focused on establishing a dialogue with the unidentified person who left a message and phone number Saturday night near a Virginia steakhouse where the latest victim was shot.

On Sunday, he had publicly pleaded with the note writer to call authorities. On Monday, he said: "The message that needs to be delivered is that we are going to respond to a message that we have received. We are preparing our response at this time."