Police searching for a six-month-old baby have sealed off an area of ground less than 300 yards from his home after finding "something of concern".
Troy Simpson: Last seen on Monday night
Troy Simpson was reported missing from his home in Smethwick in the West Midlands on Tuesday.
West Midlands Police said on Wednesday the area they had cordoned off was being treated as a crime scene.
Two men and two women - some thought to be related to Troy - are being questioned over his disappearance.
The area of wasteland off Church Road, which is at the junction of several streets, was being guarded by five uniformed officers on Wednesday night.
Forensic experts were also in an attendance and plastic sheeting was used to screen off an area beside a brook.
Police divers were seen entering the brook with flashlights as the search continued.
However, a police spokesperson said forensic tests would be required before officers could be sure what they were dealing with.
The spokesperson added: "This is being treated as a crime scene until forensic teams have attended and conducted a full investigation."
Dozens of local people gathered to watch the police operation and some residents living in nearby Dorothy Road were told they could not return to their homes,
Earlier on Wednesday Supt Andy Bebbington told a press conference he hoped Troy was still alive, but had to accept the possibility he may be dead.
Troy was wearing a tiger jumpsuit, with a gold and silver bracelet on each arm.
Officers said Troy, a mixed-race child, disappeared after being put to bed on Monday night at his home in The Uplands, Smethwick.
His grandmother noticed he had gone on Tuesday morning.
Mr Bebbington said: "It's suggested he was put to bed at approximately 9.15pm on Monday and by 6am the following morning he was not in his bed.
He added there was a chance Troy is being held by somebody and that he's alive and well.
The house in Smethwick where Troy disappeared from
He continued: "There are circumstances around this matter that lead me to believe his death is a possibility."
He appealed to people to search their houses, gardens and wasteland and stressed Troy is not thought to have been taken by an intruder.
Troy lived with his mother and grandmother although his mother is not thought to have stayed at the house during the night of his disappearance.
Police refused to say if his mother is one of the two women arrested.