One, a 45-year-old man, is suspected of attending a terrorist training camp and facilitating terrorism overseas, West Midlands police said in a statement.
The other three, a 36-year-old man from Shirley, a 44-year-old woman and her 20-year old son from Sparkhill, were detained on suspicion of facilitating terrorism overseas.
"All four arrests are connected. They were pre-planned and intelligence-led," said the head of investigations for West Midlands Counter-Terrorism Unit, Detective Superintendent Shaun Edwards.
The four were arrested at their homes.
Concern has been mounting in Britain over the number of UK nationals traveling to Syria to help rebels fighting President Bashar al-Assad. Police fear they may become radicalized by Islamists or attend terrorist training camps before returning to the UK where they could pose a security risk.
British police have already arrested 16 people on suspicion of terrorism offenses related to Syria this year, some as young as 17, compared to 24 such arrests in all of 2013.
On another note, the chief of the United Nations relief agency supporting Palestinian refugees said he is "deeply disturbed and shaken" by the despair and destruction he'd seen in a besieged camp in the Syrian capital. Filippo Grandi, the Commissioner General of UNRWA is visiting the Yarmouk refugee camp that has suffered from crippling shortages of food and medicine since it got embroiled in the Syrian civil war fighting between troops loyal to President Bashar Assad and rebels trying to oust him. Grandi said the Palestinian refugees he spoke to in Yarmouk Monday were "traumatized by what they have lived through." Many need food and medical treatment immediately, Grandi said in a statement released Tuesday. More than 100 people have died in Yarmouk since mid-2013 of illnesses exacerbated by hunger, the U.N. says. REUTERS/AP