It is easy to say, "Pray for Baltimore" and much more difficult to know what to pray. These two prayers from the BCP help.
"O Almighty God, the supreme Governor of all things, whose power no creature is able to resist, to whom it belongs justly to punish sinners, and to be merciful to those who truly repent; Save and deliver us, we humbly beseech thee, fro the hands of those intent on evil; that we, being armed with thy defense, may be preserved evermore from all perils, to glorify thee, who art the only giver of all victory; through the merits of thy Son, Jesus Christ our Lord. Amen"
"Almighty God, who has created man in thine own image; Grant us grace fearlessly to contend against evil, and to make no peace with oppression; and, that we may reverently use our freedom, help us to employ it to maintain justice among men, to the glory of thy holy Name; through Jesus Christ our Lord. Amen"